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2025-03-18iommufd: Add IOMMUFD_OBJ_VEVENTQ and IOMMUFD_CMD_VEVENTQ_ALLOCNicolin Chen
Introduce a new IOMMUFD_OBJ_VEVENTQ object for vIOMMU Event Queue that provides user space (VMM) another FD to read the vIOMMU Events. Allow a vIOMMU object to allocate vEVENTQs, with a condition that each vIOMMU can only have one single vEVENTQ per type. Add iommufd_veventq_alloc() with iommufd_veventq_ops for the new ioctl. Link: https://patch.msgid.link/r/21acf0751dd5c93846935ee06f93b9c65eff5e04.1741719725.git.nicolinc@nvidia.com Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
2025-03-18virtchnl: make proto and filter action count unsignedJan Glaza
The count field in virtchnl_proto_hdrs and virtchnl_filter_action_set should never be negative while still being valid. Changing it from int to u32 ensures proper handling of values in virtchnl messages in driverrs and prevents unintended behavior. In its current signed form, a negative count does not trigger an error in ice driver but instead results in it being treated as 0. This can lead to unexpected outcomes when processing messages. By using u32, any invalid values will correctly trigger -EINVAL, making error detection more robust. Fixes: 1f7ea1cd6a374 ("ice: Enable FDIR Configure for AVF") Reviewed-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com> Reviewed-by: Simon Horman <horms@kernel.org> Signed-off-by: Jan Glaza <jan.glaza@intel.com> Signed-off-by: Martyna Szapar-Mudlaw <martyna.szapar-mudlaw@linux.intel.com> Tested-by: Rafal Romanowski <rafal.romanowski@intel.com> Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
2025-03-18mtd: nand: Fix a kdoc commentMiquel Raynal
The max_bad_eraseblocks_per_lun member of nand_device obviously describes a number of *maximum* number of bad eraseblocks per LUN. Fix this obvious typo. Fixes: 377e517b5fa5 ("mtd: nand: Add max_bad_eraseblocks_per_lun info to memorg") Cc: <stable+noautosel@kernel.org> # fix kdoc comment Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
2025-03-18mtd: spinand: Improve spinand_info macros styleMiquel Raynal
Let's assume all these macros should not have a trailing comma, this way the caller can use a more formal and usual C writing style, as reflected in the Macronix driver. Acked-by: Pratyush Yadav <pratyush@kernel.org> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
2025-03-18fs: dedup handling of struct filename init and refcounts bumpsMateusz Guzik
No functional changes. Signed-off-by: Mateusz Guzik <mjguzik@gmail.com> Link: https://lore.kernel.org/r/20250313142744.1323281-1-mjguzik@gmail.com Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-03-18tcp: cache RTAX_QUICKACK metric in a hot cache lineEric Dumazet
tcp_in_quickack_mode() is called from input path for small packets. It calls __sk_dst_get() which reads sk->sk_dst_cache which has been put in sock_read_tx group (for good reasons). Then dst_metric(dst, RTAX_QUICKACK) also needs extra cache line misses. Cache RTAX_QUICKACK in icsk->icsk_ack.dst_quick_ack to no longer pull these cache lines for the cases a delayed ACK is scheduled. After this patch TCP receive path does not longer access sock_read_tx group. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Jason Xing <kerneljasonxing@gmail.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://patch.msgid.link/20250312083907.1931644-1-edumazet@google.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-18spi: Merge up fixesMark Brown
They are a dependency for applying some changes to the MAINTAINERS file.
2025-03-18inet: frags: change inet_frag_kill() to defer refcount updatesEric Dumazet
In the following patch, we no longer assume inet_frag_kill() callers own a reference. Consuming two refcounts from inet_frag_kill() would lead in UAF. Propagate the pointer to the refs that will be consumed later by the final inet_frag_putn() call. Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250312082250.1803501-4-edumazet@google.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-18inet: frags: add inet_frag_putn() helperEric Dumazet
inet_frag_putn() can release multiple references in one step. Use it in inet_frags_free_cb(). Replace inet_frag_put(X) with inet_frag_putn(X, 1) Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250312082250.1803501-2-edumazet@google.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-18net: skbuff: Remove unused skb_add_data()Yue Haibing
Since commit a4ea4c477619 ("rxrpc: Don't use a ring buffer for call Tx queue") this function is not used anymore. Signed-off-by: Yue Haibing <yuehaibing@huawei.com> Reviewed-by: Simon Horman <horms@kernel.org> Link: https://patch.msgid.link/20250312063450.183652-1-yuehaibing@huawei.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-18Merge tag 'batadv-next-pullrequest-20250313' of ↵Paolo Abeni
git://git.open-mesh.org/linux-merge Simon Wunderlich says: ==================== This feature/cleanup patchset includes the following patches: - bump version strings, by Simon Wunderlich - drop batadv_priv_debug_log struct, by Sven Eckelmann - adopt netdev_hold() / netdev_put(), by Eric Dumazet - add support for jumbo frames, by Sven Eckelmann - use consistent name for mesh interface, by Sven Eckelmann - cleanup B.A.T.M.A.N. IV OGM aggregation handling, by Sven Eckelmann (4 patches) - add missing newlines for log macros, by Sven Eckelmann * tag 'batadv-next-pullrequest-20250313' of git://git.open-mesh.org/linux-merge: batman-adv: add missing newlines for log macros batman-adv: Limit aggregation size to outgoing MTU batman-adv: Use actual packet count for aggregated packets batman-adv: Switch to bitmap helper for aggregation handling batman-adv: Limit number of aggregated packets directly batman-adv: Use consistent name for mesh interface batman-adv: Add support for jumbo frames batman-adv: adopt netdev_hold() / netdev_put() batman-adv: Drop batadv_priv_debug_log struct batman-adv: Start new development cycle ==================== Link: https://patch.msgid.link/20250313164519.72808-1-sw@simonwunderlich.de Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-18udp_tunnel: use static call for GRO hooks when possiblePaolo Abeni
It's quite common to have a single UDP tunnel type active in the whole system. In such a case we can replace the indirect call for the UDP tunnel GRO callback with a static call. Add the related accounting in the control path and switch to static call when possible. To keep the code simple use a static array for the registered tunnel types, and size such array based on the kernel config. Reviewed-by: Willem de Bruijn <willemb@google.com> Link: https://patch.msgid.link/6fd1f9c7651151493ecab174e7b8386a1534170d.1741718157.git.pabeni@redhat.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-18udp_tunnel: create a fastpath GRO lookup.Paolo Abeni
Most UDP tunnels bind a socket to a local port, with ANY address, no peer and no interface index specified. Additionally it's quite common to have a single tunnel device per namespace. Track in each namespace the UDP tunnel socket respecting the above. When only a single one is present, store a reference in the netns. When such reference is not NULL, UDP tunnel GRO lookup just need to match the incoming packet destination port vs the socket local port. The tunnel socket never sets the reuse[port] flag[s]. When bound to no address and interface, no other socket can exist in the same netns matching the specified local port. Matching packets with non-local destination addresses will be aggregated, and eventually segmented as needed - no behavior changes intended. Note that the UDP tunnel socket reference is stored into struct netns_ipv4 for both IPv4 and IPv6 tunnels. That is intentional to keep all the fastpath-related netns fields in the same struct and allow cacheline-based optimization. Currently both the IPv4 and IPv6 socket pointer share the same cacheline as the `udp_table` field. Reviewed-by: Willem de Bruijn <willemb@google.com> Link: https://patch.msgid.link/4d5c319c4471161829f50cb8436841de81a5edae.1741718157.git.pabeni@redhat.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-18net: mana: Support holes in device list reply msgHaiyang Zhang
According to GDMA protocol, holes (zeros) are allowed at the beginning or middle of the gdma_list_devices_resp message. The existing code cannot properly handle this, and may miss some devices in the list. To fix, scan the entire list until the num_of_devs are found, or until the end of the list. Cc: stable@vger.kernel.org Fixes: ca9c54d2d6a5 ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)") Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com> Reviewed-by: Long Li <longli@microsoft.com> Reviewed-by: Shradha Gupta <shradhagupta@microsoft.com> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com> Link: https://patch.msgid.link/1741723974-1534-1-git-send-email-haiyangz@microsoft.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-18RDMA/mlx5: Support optional-counters binding for QPsPatrisious Haddad
Add support to allow optional-counters binding to a QP, whereas when a bind operation is requested depending on the counter optional-counter binding state the driver will determine if to also add optional-counters to this QP binding. The optional-counter binding is done by simply adding a steering rule for the specific optional-counter condition with the additional match over that QP number. Note that optional-counters per QP rules are handled on an earlier prio than per device counters, and per device counter correctness is maintained by core whereas it is responsible to sum active counters when checking device counter and to add them to history count when they are deallocated. Signed-off-by: Patrisious Haddad <phaddad@nvidia.com> Reviewed-by: Mark Bloch <mbloch@nvidia.com> Link: https://patch.msgid.link/2cad1b891a6641ae61fe8d92f867e1059121813a.1741875070.git.leon@kernel.org Signed-off-by: Leon Romanovsky <leon@kernel.org>
2025-03-18RDMA/core: Pass port to counter bind/unbind operationsPatrisious Haddad
This will be useful for the next patches in the series since port number is needed for optional counters binding and unbinding. Note that this change is needed since when the operation is done qp->port isn't necessarily initialized yet and can't be used. Signed-off-by: Patrisious Haddad <phaddad@nvidia.com> Reviewed-by: Mark Bloch <mbloch@nvidia.com> Link: https://patch.msgid.link/b6f6797844acbd517358e8d2a270ea9b3e6ecba1.1741875070.git.leon@kernel.org Signed-off-by: Leon Romanovsky <leon@kernel.org>
2025-03-18RDMA/core: Add support to optional-counters binding configurationPatrisious Haddad
Whenever a new counter is created, save inside it the user requested configuration for optional-counters binding, for manual configuration it is requested directly by the user and for the automatic configuration it depends on if the automatic binding was enabled with or without optional-counters binding. This argument will later be used by the driver to determine if to bind the optional-counters as well or not when trying to bind this counter to a QP. It indicates that when binding counters to a QP we also want the currently enabled link optional-counters to be bound as well. Signed-off-by: Patrisious Haddad <phaddad@nvidia.com> Reviewed-by: Mark Bloch <mbloch@nvidia.com> Link: https://patch.msgid.link/82f1c357606a16932979ef9a5910122675c74a3a.1741875070.git.leon@kernel.org Signed-off-by: Leon Romanovsky <leon@kernel.org>
2025-03-18RDMA/core: Create and destroy rdma_counter using rdma_zalloc_drv_obj()Patrisious Haddad
Change rdma_counter allocation to use rdma_zalloc_drv_obj() instead of, explicitly allocating at core, in order to be contained inside driver specific structures. Adjust all drivers that use it to have their containing structure, and add driver specific initialization operation. This change is needed to allow upcoming patches to implement optional-counters binding whereas inside each driver specific counter struct his bound optional-counters will be maintained. Signed-off-by: Patrisious Haddad <phaddad@nvidia.com> Reviewed-by: Mark Bloch <mbloch@nvidia.com> Link: https://patch.msgid.link/a5a484f421fc2e5595158e61a354fba43272b02d.1741875070.git.leon@kernel.org Signed-off-by: Leon Romanovsky <leon@kernel.org>
2025-03-18RDMA/mlx5: Add optional counters for RDMA_TX/RX_packets/bytesPatrisious Haddad
Add the following optional counters: rdma_tx_packets,rdma_rx_bytes,rdma_rx_packets,rdma_tx_bytes. Which counts all RDMA packets/bytes sent and received per link. Note that since each direction packet and byte counter are shared, the counter is only reset when both counters of that direction are removed. But from user-perspective each can be enabled/disabled separately. The counters can be enabled using: sudo rdma stat set link rocep8s0f0/1 optional-counters rdma_tx_packets And can be seen using: rdma stat -j show link rocep8s0f0/1 Signed-off-by: Patrisious Haddad <phaddad@nvidia.com> Reviewed-by: Mark Bloch <mbloch@nvidia.com> Link: https://patch.msgid.link/9f2753ad636f21704416df64b47395c8991d1123.1741875070.git.leon@kernel.org Signed-off-by: Leon Romanovsky <leon@kernel.org>
2025-03-18ata: libata-core: Add ATA_QUIRK_NO_LPM_ON_ATI for certain Samsung SSDsNiklas Cassel
Before commit 7627a0edef54 ("ata: ahci: Drop low power policy board type") the ATI AHCI controllers specified board type 'board_ahci' rather than board type 'board_ahci'. This means that LPM was historically not enabled for the ATI AHCI controllers. By looking at commit 7a8526a5cd51 ("libata: Add ATA_HORKAGE_NO_NCQ_ON_ATI for Samsung 860 and 870 SSD."), it is clear that, for some unknown reason, that Samsung SSDs do not play nice with ATI AHCI controllers. (When using other AHCI controllers, NCQ can be enabled on these Samsung SSDs without issues.) In a similar way, from user reports, it is clear the ATI AHCI controllers can enable LPM on e.g. Maxtor HDDs perfectly fine, but when enabling LPM on certain Samsung SSDs, things break. (E.g. the SSDs will not get detected by the ATI AHCI controller even after a COMRESET.) Yet, when using LPM on these Samsung SSDs with other AHCI controllers, e.g. Intel AHCI controllers, these Samsung drives appear to work perfectly fine. Considering that the combination of ATI + Samsung, for some unknown reason, does not seem to work well, disable LPM when detecting an ATI AHCI controller with a problematic Samsung SSD. Apply this new ATA_QUIRK_NO_LPM_ON_ATI quirk for all Samsung SSDs that have already been reported to not play nice with ATI (ATA_QUIRK_NO_NCQ_ON_ATI). Fixes: 7627a0edef54 ("ata: ahci: Drop low power policy board type") Suggested-by: Hans de Goede <hdegoede@redhat.com> Reported-by: Eric <eric.4.debian@grabatoulnz.fr> Closes: https://lore.kernel.org/linux-ide/Z8SBZMBjvVXA7OAK@eldamar.lan/ Tested-by: Eric <eric.4.debian@grabatoulnz.fr> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20250317170348.1748671-2-cassel@kernel.org Signed-off-by: Niklas Cassel <cassel@kernel.org>
2025-03-18Merge net-next/main to resolve conflictsJohannes Berg
There are a few conflicts between the work that went into wireless and that's here now, resolve them. Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-03-18net: phy: drop phy_settings and the associated lookup helpersMaxime Chevallier
The phy_settings array is no longer relevant as it has now been replaced by the link_caps array and associated phy_caps helpers. Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com> Link: https://patch.msgid.link/20250307173611.129125-11-maxime.chevallier@bootlin.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-18net: phy: phy_caps: Move phy_speeds to phy_capsMaxime Chevallier
Use the newly introduced link_capabilities array to derive the list of possible speeds when given a combination of linkmodes. As link_capabilities is indexed by speed, we don't have to iterate the whole phy_settings array. Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com> Link: https://patch.msgid.link/20250307173611.129125-4-maxime.chevallier@bootlin.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-18net: ethtool: Export the link_mode_params definitionsMaxime Chevallier
link_mode_params contains a lookup table of all 802.3 link modes that are currently supported with structured data about each mode's speed, duplex, number of lanes and mediums. As a preparation for a port representation, export that table for the rest of the net stack to use. Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com> Link: https://patch.msgid.link/20250307173611.129125-2-maxime.chevallier@bootlin.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-03-17Merge tag 'mm-hotfixes-stable-2025-03-17-20-09' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull misc hotfixes from Andrew Morton: "15 hotfixes. 7 are cc:stable and the remainder address post-6.13 issues or aren't considered necessary for -stable kernels. 13 are for MM and the other two are for squashfs and procfs. All are singletons. Please see the individual changelogs for details" * tag 'mm-hotfixes-stable-2025-03-17-20-09' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: mm/page_alloc: fix memory accept before watermarks gets initialized mm: decline to manipulate the refcount on a slab page memcg: drain obj stock on cpu hotplug teardown mm/huge_memory: drop beyond-EOF folios with the right number of refs selftests/mm: run_vmtests.sh: fix half_ufd_size_MB calculation mm: fix error handling in __filemap_get_folio() with FGP_NOWAIT mm: memcontrol: fix swap counter leak from offline cgroup mm/vma: do not register private-anon mappings with khugepaged during mmap squashfs: fix invalid pointer dereference in squashfs_cache_delete mm/migrate: fix shmem xarray update during migration mm/hugetlb: fix surplus pages in dissolve_free_huge_page() mm/damon/core: initialize damos->walk_completed in damon_new_scheme() mm/damon: respect core layer filters' allowance decision on ops layer filemap: move prefaulting out of hot write path proc: fix UAF in proc_get_inode()
2025-03-17mm: page_alloc: defrag_mode kswapd/kcompactd watermarksJohannes Weiner
The previous patch added pageblock_order reclaim to kswapd/kcompactd, which helps, but produces only one block at a time. Allocation stalls and THP failure rates are still higher than they could be. To adequately reflect ALLOC_NOFRAGMENT demand for pageblocks, change the watermarking for kswapd & kcompactd: instead of targeting the high watermark in order-0 pages and checking for one suitable block, simply require that the high watermark is entirely met in pageblocks. To this end, track the number of free pages within contiguous pageblocks, then change pgdat_balanced() and compact_finished() to check watermarks against this new value. This further reduces THP latencies and allocation stalls, and improves THP success rates against the previous patch: DEFRAGMODE-ASYNC DEFRAGMODE-ASYNC-WMARKS Hugealloc Time mean 34300.36 ( +0.00%) 28904.00 ( -15.73%) Hugealloc Time stddev 36390.42 ( +0.00%) 33464.37 ( -8.04%) Kbuild Real time 196.13 ( +0.00%) 196.59 ( +0.23%) Kbuild User time 1234.74 ( +0.00%) 1231.67 ( -0.25%) Kbuild System time 62.62 ( +0.00%) 59.10 ( -5.54%) THP fault alloc 57054.53 ( +0.00%) 63223.67 ( +10.81%) THP fault fallback 11581.40 ( +0.00%) 5412.47 ( -53.26%) Direct compact fail 107.80 ( +0.00%) 59.07 ( -44.79%) Direct compact success 4.53 ( +0.00%) 2.80 ( -31.33%) Direct compact success rate % 3.20 ( +0.00%) 3.99 ( +18.66%) Compact daemon scanned migrate 5461033.93 ( +0.00%) 2267500.33 ( -58.48%) Compact daemon scanned free 5824897.93 ( +0.00%) 2339773.00 ( -59.83%) Compact direct scanned migrate 58336.93 ( +0.00%) 47659.93 ( -18.30%) Compact direct scanned free 32791.87 ( +0.00%) 40729.67 ( +24.21%) Compact total migrate scanned 5519370.87 ( +0.00%) 2315160.27 ( -58.05%) Compact total free scanned 5857689.80 ( +0.00%) 2380502.67 ( -59.36%) Alloc stall 2424.60 ( +0.00%) 638.87 ( -73.62%) Pages kswapd scanned 2657018.33 ( +0.00%) 4002186.33 ( +50.63%) Pages kswapd reclaimed 559583.07 ( +0.00%) 718577.80 ( +28.41%) Pages direct scanned 722094.07 ( +0.00%) 355172.73 ( -50.81%) Pages direct reclaimed 107257.80 ( +0.00%) 31162.80 ( -70.95%) Pages total scanned 3379112.40 ( +0.00%) 4357359.07 ( +28.95%) Pages total reclaimed 666840.87 ( +0.00%) 749740.60 ( +12.43%) Swap out 77238.20 ( +0.00%) 110084.33 ( +42.53%) Swap in 11712.80 ( +0.00%) 24457.00 ( +108.80%) File refaults 143438.80 ( +0.00%) 188226.93 ( +31.22%) Also of note is that compaction work overall is reduced. The reason for this is that when free pageblocks are more readily available, allocations are also much more likely to get physically placed in LRU order, instead of being forced to scavenge free space here and there. This means that reclaim by itself has better chances of freeing up whole blocks, and the system relies less on compaction. Comparing all changes to the vanilla kernel: VANILLA DEFRAGMODE-ASYNC-WMARKS Hugealloc Time mean 52739.45 ( +0.00%) 28904.00 ( -45.19%) Hugealloc Time stddev 56541.26 ( +0.00%) 33464.37 ( -40.81%) Kbuild Real time 197.47 ( +0.00%) 196.59 ( -0.44%) Kbuild User time 1240.49 ( +0.00%) 1231.67 ( -0.71%) Kbuild System time 70.08 ( +0.00%) 59.10 ( -15.45%) THP fault alloc 46727.07 ( +0.00%) 63223.67 ( +35.30%) THP fault fallback 21910.60 ( +0.00%) 5412.47 ( -75.29%) Direct compact fail 195.80 ( +0.00%) 59.07 ( -69.48%) Direct compact success 7.93 ( +0.00%) 2.80 ( -57.46%) Direct compact success rate % 3.51 ( +0.00%) 3.99 ( +10.49%) Compact daemon scanned migrate 3369601.27 ( +0.00%) 2267500.33 ( -32.71%) Compact daemon scanned free 5075474.47 ( +0.00%) 2339773.00 ( -53.90%) Compact direct scanned migrate 161787.27 ( +0.00%) 47659.93 ( -70.54%) Compact direct scanned free 163467.53 ( +0.00%) 40729.67 ( -75.08%) Compact total migrate scanned 3531388.53 ( +0.00%) 2315160.27 ( -34.44%) Compact total free scanned 5238942.00 ( +0.00%) 2380502.67 ( -54.56%) Alloc stall 2371.07 ( +0.00%) 638.87 ( -73.02%) Pages kswapd scanned 2160926.73 ( +0.00%) 4002186.33 ( +85.21%) Pages kswapd reclaimed 533191.07 ( +0.00%) 718577.80 ( +34.77%) Pages direct scanned 400450.33 ( +0.00%) 355172.73 ( -11.31%) Pages direct reclaimed 94441.73 ( +0.00%) 31162.80 ( -67.00%) Pages total scanned 2561377.07 ( +0.00%) 4357359.07 ( +70.12%) Pages total reclaimed 627632.80 ( +0.00%) 749740.60 ( +19.46%) Swap out 47959.53 ( +0.00%) 110084.33 ( +129.53%) Swap in 7276.00 ( +0.00%) 24457.00 ( +236.10%) File refaults 138043.00 ( +0.00%) 188226.93 ( +36.35%) THP allocation latencies and %sys time are down dramatically. THP allocation failures are down from nearly 50% to 8.5%. And to recall previous data points, the success rates are steady and reliable without the cumulative deterioration of fragmentation events. Compaction work is down overall. Direct compaction work especially is drastically reduced. As an aside, its success rate of 4% indicates there is room for improvement. For now it's good to rely on it less. Reclaim work is up overall, however direct reclaim work is down. Part of the increase can be attributed to a higher use of THPs, which due to internal fragmentation increase the memory footprint. This is not necessarily an unexpected side-effect for users of THP. However, taken both points together, there may well be some opportunities for fine tuning in the reclaim/compaction coordination. [hannes@cmpxchg.org: fix squawks from rebasing] Link: https://lkml.kernel.org/r/20250314210558.GD1316033@cmpxchg.org Link: https://lkml.kernel.org/r/20250313210647.1314586-6-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm: compaction: push watermark into compaction_suitable() callersJohannes Weiner
Patch series "mm: reliable huge page allocator". This series makes changes to the allocator and reclaim/compaction code to try harder to avoid fragmentation. As a result, this makes huge page allocations cheaper, more reliable and more sustainable. It's a subset of the huge page allocator RFC initially proposed here: https://lore.kernel.org/lkml/20230418191313.268131-1-hannes@cmpxchg.org/ The following results are from a kernel build test, with additional concurrent bursts of THP allocations on a memory-constrained system. Comparing before and after the changes over 15 runs: before after Hugealloc Time mean 52739.45 ( +0.00%) 28904.00 ( -45.19%) Hugealloc Time stddev 56541.26 ( +0.00%) 33464.37 ( -40.81%) Kbuild Real time 197.47 ( +0.00%) 196.59 ( -0.44%) Kbuild User time 1240.49 ( +0.00%) 1231.67 ( -0.71%) Kbuild System time 70.08 ( +0.00%) 59.10 ( -15.45%) THP fault alloc 46727.07 ( +0.00%) 63223.67 ( +35.30%) THP fault fallback 21910.60 ( +0.00%) 5412.47 ( -75.29%) Direct compact fail 195.80 ( +0.00%) 59.07 ( -69.48%) Direct compact success 7.93 ( +0.00%) 2.80 ( -57.46%) Direct compact success rate % 3.51 ( +0.00%) 3.99 ( +10.49%) Compact daemon scanned migrate 3369601.27 ( +0.00%) 2267500.33 ( -32.71%) Compact daemon scanned free 5075474.47 ( +0.00%) 2339773.00 ( -53.90%) Compact direct scanned migrate 161787.27 ( +0.00%) 47659.93 ( -70.54%) Compact direct scanned free 163467.53 ( +0.00%) 40729.67 ( -75.08%) Compact total migrate scanned 3531388.53 ( +0.00%) 2315160.27 ( -34.44%) Compact total free scanned 5238942.00 ( +0.00%) 2380502.67 ( -54.56%) Alloc stall 2371.07 ( +0.00%) 638.87 ( -73.02%) Pages kswapd scanned 2160926.73 ( +0.00%) 4002186.33 ( +85.21%) Pages kswapd reclaimed 533191.07 ( +0.00%) 718577.80 ( +34.77%) Pages direct scanned 400450.33 ( +0.00%) 355172.73 ( -11.31%) Pages direct reclaimed 94441.73 ( +0.00%) 31162.80 ( -67.00%) Pages total scanned 2561377.07 ( +0.00%) 4357359.07 ( +70.12%) Pages total reclaimed 627632.80 ( +0.00%) 749740.60 ( +19.46%) Swap out 47959.53 ( +0.00%) 110084.33 ( +129.53%) Swap in 7276.00 ( +0.00%) 24457.00 ( +236.10%) File refaults 138043.00 ( +0.00%) 188226.93 ( +36.35%) THP latencies are cut in half, and failure rates are cut by 75%. These metrics also hold up over time, while the vanilla kernel sees a steady downward trend in success rates with each subsequent run, owed to the cumulative effects of fragmentation. A more detailed discussion of results is in the patch changelogs. The patches first introduce a vm.defrag_mode sysctl, which enforces the existing ALLOC_NOFRAGMENT alloc flag until after reclaim and compaction have run. They then change kswapd and kcompactd to target pageblocks, which boosts success in the ALLOC_NOFRAGMENT hotpaths. Patches #1 and #2 are somewhat unrelated cleanups, but touch the same code and so are included here to avoid conflicts from re-ordering. This patch (of 5): compaction_suitable() hardcodes the min watermark, with a boost to the low watermark for costly orders. However, compaction_ready() requires order-0 at the high watermark. It currently checks the marks twice. Make the watermark a parameter to compaction_suitable() and have the callers pass in what they require: - compaction_zonelist_suitable() is used by the direct reclaim path, so use the min watermark. - compact_suit_allocation_order() has a watermark in context derived from cc->alloc_flags. The only quirk is that kcompactd doesn't initialize cc->alloc_flags explicitly. There is a direct check in kcompactd_do_work() that passes ALLOC_WMARK_MIN, but there is another check downstack in compact_zone() that ends up passing the unset alloc_flags. Since they default to 0, and that coincides with ALLOC_WMARK_MIN, it is correct. But it's subtle. Set cc->alloc_flags explicitly. - should_continue_reclaim() is direct reclaim, use the min watermark. - Finally, consolidate the two checks in compaction_ready() to a single compaction_suitable() call passing the high watermark. There is a tiny change in behavior: before, compaction_suitable() would check order-0 against min or low, depending on costly order. Then there'd be another high watermark check. Now, the high watermark is passed to compaction_suitable(), and the costly order-boost (low - min) is added on top. This means compaction_ready() sets a marginally higher target for free pages. In a kernelbuild + THP pressure test, though, this didn't show any measurable negative effects on memory pressure or reclaim rates. As the comment above the check says, reclaim is usually stopped short on should_continue_reclaim(), and this just defines the worst-case reclaim cutoff in case compaction is not making any headway. [hughd@google.com: stop oops on out-of-range highest_zoneidx] Link: https://lkml.kernel.org/r/005ace8b-07fa-01d4-b54b-394a3e029c07@google.com Link: https://lkml.kernel.org/r/20250313210647.1314586-1-hannes@cmpxchg.org Link: https://lkml.kernel.org/r/20250313210647.1314586-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Zi Yan <ziy@nvidia.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/page_alloc: add trace event for totalreserve_pages calculationMartin Liu
This commit introduces a new trace event, `mm_calculate_totalreserve_pages`, which reports the new reserve value at the exact time when it takes effect. The `totalreserve_pages` value represents the total amount of memory reserved across all zones and nodes in the system. This reserved memory is crucial for ensuring that critical kernel operations have access to sufficient memory, even under memory pressure. By tracing the `totalreserve_pages` value, developers can gain insights that how the total reserved memory changes over time. Link: https://lkml.kernel.org/r/20250308034606.2036033-4-liumartin@google.com Signed-off-by: Martin Liu <liumartin@google.com> Acked-by: David Rientjes <rientjes@google.com> Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/page_alloc: add trace event for per-zone lowmem reserve setupMartin Liu
This commit introduces the `mm_setup_per_zone_lowmem_reserve` trace event,which provides detailed insights into the kernel's per-zone lowmem reserve configuration. The trace event provides precise timestamps, allowing developers to 1. Correlate lowmem reserve changes with specific kernel events and able to diagnose unexpected kswapd or direct reclaim behavior triggered by dynamic changes in lowmem reserve. 2. Know memory allocation failures that occur due to insufficient lowmem reserve, by precisely correlating allocation attempts with reserve adjustments. Link: https://lkml.kernel.org/r/20250308034606.2036033-3-liumartin@google.com Signed-off-by: Martin Liu <liumartin@google.com> Acked-by: David Rientjes <rientjes@google.com> Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/page_alloc: add trace event for per-zone watermark setupMartin Liu
Patch series "Add tracepoints for lowmem reserves, watermarks and totalreserve_pages", v2. This patchset introduces tracepoints to track changes in the lowmem reserves, watermarks and totalreserve_pages. This helps to track the exact timing of such changes and understand their relation to reclaim activities. The tracepoints added are: mm_setup_per_zone_lowmem_reserve mm_setup_per_zone_wmarks mm_calculate_totalreserve_pagesi This patch (of 3): This commit introduces the `mm_setup_per_zone_wmarks` trace event, which provides detailed insights into the kernel's per-zone watermark configuration, offering precise timing and the ability to correlate watermark changes with specific kernel events. While `/proc/zoneinfo` provides some information about zone watermarks, this trace event offers: 1. The ability to link watermark changes to specific kernel events and logic. 2. The ability to capture rapid or short-lived changes in watermarks that may be missed by user-space polling 3. Diagnosing unexpected kswapd activity or excessive direct reclaim triggered by rapidly changing watermarks. Link: https://lkml.kernel.org/r/20250308034606.2036033-1-liumartin@google.com Link: https://lkml.kernel.org/r/20250308034606.2036033-2-liumartin@google.com Signed-off-by: Martin Liu <liumartin@google.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Martin Liu <liumartin@google.com> Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17drivers/base/memory: correct the field name in the headerGavin Shan
Replace @blocks with @memory_blocks to match with the definition of struct memory_group. Link: https://lkml.kernel.org/r/20250311233045.148943-3-gshan@redhat.com Signed-off-by: Gavin Shan <gshan@redhat.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Oscar Salvador <osalvador@suse.de> Cc: Danilo Krummrich <dakr@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17drivers/base/memory: improve add_boot_memory_block()Gavin Shan
Patch series "drivers/base/memory: Two cleanups", v3. Two cleanups to drivers/base/memory. This patch (of 2)L It's unnecessary to count the present sections for the specified block since the block will be added if any section in the block is present. Besides, for_each_present_section_nr() can be reused as Andrew Morton suggested. Improve by using for_each_present_section_nr() and dropping the unnecessary @section_count. No functional changes intended. Link: https://lkml.kernel.org/r/20250311233045.148943-1-gshan@redhat.com Link: https://lkml.kernel.org/r/20250311233045.148943-2-gshan@redhat.com Signed-off-by: Gavin Shan <gshan@redhat.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Oscar Salvador <osalvador@suse.de> Cc: Danilo Krummrich <dakr@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/filemap: use xas_try_split() in __filemap_add_folio()Zi Yan
Patch series "Minimize xa_node allocation during xarry split", v3. When splitting a multi-index entry in XArray from order-n to order-m, existing xas_split_alloc()+xas_split() approach requires 2^(n % XA_CHUNK_SHIFT) xa_node allocations. But its callers, __filemap_add_folio() and shmem_split_large_entry(), use at most 1 xa_node. To minimize xa_node allocation and remove the limitation of no split from order-12 (or above) to order-0 (or anything between 0 and 5)[1], xas_try_split() was added[2], which allocates (n / XA_CHUNK_SHIFT - m / XA_CHUNK_SHIFT) xa_node. It is used for non-uniform folio split, but can be used by __filemap_add_folio() and shmem_split_large_entry(). xas_split_alloc() and xas_split() split an order-9 to order-0: --------------------------------- | | | | | | | | | | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | | | | | | | | | | --------------------------------- | | | | ------- --- --- ------- | | ... | | V V V V ----------- ----------- ----------- ----------- | xa_node | | xa_node | ... | xa_node | | xa_node | ----------- ----------- ----------- ----------- xas_try_split() splits an order-9 to order-0: --------------------------------- | | | | | | | | | | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | | | | | | | | | | --------------------------------- | | V ----------- | xa_node | ----------- xas_try_split() is designed to be called iteratively with n = m + 1. xas_try_split_mini_order() is added to minmize the number of calls to xas_try_split() by telling the caller the next minimal order to split to instead of n - 1. Splitting order-n to order-m when m= l * XA_CHUNK_SHIFT does not require xa_node allocation and requires 1 xa_node when n=l * XA_CHUNK_SHIFT and m = n - 1, so it is OK to use xas_try_split() with n > m + 1 when no new xa_node is needed. xfstests quick group test passed on xfs and tmpfs. [1] https://lore.kernel.org/linux-mm/Z6YX3RznGLUD07Ao@casper.infradead.org/ [2] https://lore.kernel.org/linux-mm/20250226210032.2044041-1-ziy@nvidia.com/ This patch (of 2): During __filemap_add_folio(), a shadow entry is covering n slots and a folio covers m slots with m < n is to be added. Instead of splitting all n slots, only the m slots covered by the folio need to be split and the remaining n-m shadow entries can be retained with orders ranging from m to n-1. This method only requires (n/XA_CHUNK_SHIFT) - (m/XA_CHUNK_SHIFT) new xa_nodes instead of (n % XA_CHUNK_SHIFT) * ((n/XA_CHUNK_SHIFT) - (m/XA_CHUNK_SHIFT)) new xa_nodes, compared to the original xas_split_alloc() + xas_split() one. For example, to insert an order-0 folio when an order-9 shadow entry is present (assuming XA_CHUNK_SHIFT is 6), 1 xa_node is needed instead of 8. xas_try_split_min_order() is introduced to reduce the number of calls to xas_try_split() during split. Link: https://lkml.kernel.org/r/20250314222113.711703-1-ziy@nvidia.com Link: https://lkml.kernel.org/r/20250314222113.711703-2-ziy@nvidia.com Signed-off-by: Zi Yan <ziy@nvidia.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kairui Song <kasong@tencent.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mattew Wilcox <willy@infradead.org> Cc: David Hildenbrand <david@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Yang Shi <yang@os.amperecomputing.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/truncate: use folio_split() in truncate operationZi Yan
Instead of splitting the large folio uniformly during truncation, try to use buddy allocator like folio_split() at the start and the end of a truncation range to minimize the number of resulting folios if it is supported. try_folio_split() is introduced to use folio_split() if supported and it falls back to uniform split otherwise. For example, to truncate a order-4 folio [0, 1, 2, 3, 4, 5, ..., 15] between [3, 10] (inclusive), folio_split() splits the folio at 3 to [0,1], [2], [3], [4..7], [8..15] and [3], [4..7] can be dropped and [8..15] is kept with zeros in [8..10], then another folio_split() is done at 10, so [8..10] can be dropped. One possible optimization is to make folio_split() to split a folio based on a given range, like [3..10] above. But that complicates folio_split(), so it will be investigated when necessary. Link: https://lkml.kernel.org/r/20250226210032.2044041-8-ziy@nvidia.com Link: https://lkml.kernel.org/r/20250307174001.242794-8-ziy@nvidia.com Signed-off-by: Zi Yan <ziy@nvidia.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Yang Shi <yang@os.amperecomputing.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Kairui Song <kasong@tencent.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17xarray: add xas_try_split() to split a multi-index entryZi Yan
Patch series "Buddy allocator like (or non-uniform) folio split", v10. This patchset adds a new buddy allocator like (or non-uniform) large folio split from a order-n folio to order-m with m < n. It reduces 1. the total number of after-split folios from 2^(n-m) to n-m+1; 2. the amount of memory needed for multi-index xarray split from 2^(n/6-m/6) to n/6-m/6, assuming XA_CHUNK_SHIFT=6; 3. keep more large folios after a split from all order-m folios to order-(n-1) to order-m folios. For example, to split an order-9 to order-0, folio split generates 10 (or 11 for anonymous memory) folios instead of 512, allocates 1 xa_node instead of 8, and leaves 1 order-8, 1 order-7, ..., 1 order-1 and 2 order-0 folios (or 4 order-0 for anonymous memory) instead of 512 order-0 folios. Instead of duplicating existing split_huge_page*() code, __folio_split() is introduced as the shared backend code for both split_huge_page_to_list_to_order() and folio_split(). __folio_split() can support both uniform split and buddy allocator like (or non-uniform) split. All existing split_huge_page*() users can be gradually converted to use folio_split() if possible. In this patchset, I converted truncate_inode_partial_folio() to use folio_split(). xfstests quick group passed for both tmpfs and xfs. I also semi-replicated Hugh's test[12] and ran it without any issue for almost 24 hours. This patch (of 8): A preparation patch for non-uniform folio split, which always split a folio into half iteratively, and minimal xarray entry split. Currently, xas_split_alloc() and xas_split() always split all slots from a multi-index entry. They cost the same number of xa_node as the to-be-split slots. For example, to split an order-9 entry, which takes 2^(9-6)=8 slots, assuming XA_CHUNK_SHIFT is 6 (!CONFIG_BASE_SMALL), 8 xa_node are needed. Instead xas_try_split() is intended to be used iteratively to split the order-9 entry into 2 order-8 entries, then split one order-8 entry, based on the given index, to 2 order-7 entries, ..., and split one order-1 entry to 2 order-0 entries. When splitting the order-6 entry and a new xa_node is needed, xas_try_split() will try to allocate one if possible. As a result, xas_try_split() would only need 1 xa_node instead of 8. When a new xa_node is needed during the split, xas_try_split() can try to allocate one but no more. -ENOMEM will be return if a node cannot be allocated. -EINVAL will be return if a sibling node is split or cascade split happens, where two or more new nodes are needed, and these are not supported by xas_try_split(). xas_split_alloc() and xas_split() split an order-9 to order-0: --------------------------------- | | | | | | | | | | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | | | | | | | | | | --------------------------------- | | | | ------- --- --- ------- | | ... | | V V V V ----------- ----------- ----------- ----------- | xa_node | | xa_node | ... | xa_node | | xa_node | ----------- ----------- ----------- ----------- xas_try_split() splits an order-9 to order-0: --------------------------------- | | | | | | | | | | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | | | | | | | | | | --------------------------------- | | V ----------- | xa_node | ----------- Link: https://lkml.kernel.org/r/20250307174001.242794-1-ziy@nvidia.com Link: https://lkml.kernel.org/r/20250307174001.242794-2-ziy@nvidia.com Signed-off-by: Zi Yan <ziy@nvidia.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Yang Shi <yang@os.amperecomputing.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Kairui Song <kasong@tencent.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm: page_ext: add an iteration API for page extensionsLuiz Capitulino
Patch series "mm: page_ext: Introduce new iteration API", v3. Introduction ============ [ Thanks to David Hildenbrand for identifying the root cause of this issue and proving guidance on how to fix it. The new API idea, bugs and misconceptions are all mine though ] Currently, trying to reserve 1G pages with page_owner=on and sparsemem causes a crash. The reproducer is very simple: 1. Build the kernel with CONFIG_SPARSEMEM=y and the table extensions 2. Pass 'default_hugepagesz=1 page_owner=on' in the kernel command-line 3. Reserve one 1G page at run-time, this should crash (see patch 1 for backtrace) [ A crash with page_table_check is also possible, but harder to trigger ] Apparently, starting with commit cf54f310d0d3 ("mm/hugetlb: use __GFP_COMP for gigantic folios") we now pass the full allocation order to page extension clients and the page extension implementation assumes that all PFNs of an allocation range will be stored in the same memory section (which is not true for 1G pages). To fix this, this series introduces a new iteration API for page extension objects. The API checks if the next page extension object can be retrieved from the current section or if it needs to look up for it in another section. Please, find all details in patch 1. I tested this series on arm64 and x86 by reserving 1G pages at run-time and doing kernel builds (always with page_owner=on and page_table_check=on). This patch (of 3): The page extension implementation assumes that all page extensions of a given page order are stored in the same memory section. The function page_ext_next() relies on this assumption by adding an offset to the current object to return the next adjacent page extension. This behavior works as expected for flatmem but fails for sparsemem when using 1G pages. The commit cf54f310d0d3 ("mm/hugetlb: use __GFP_COMP for gigantic folios") exposes this issue, making it possible for a crash when using page_owner or page_table_check page extensions. The problem is that for 1G pages, the page extensions may span memory section boundaries and be stored in different memory sections. This issue was not visible before commit cf54f310d0d3 ("mm/hugetlb: use __GFP_COMP for gigantic folios") because alloc_contig_pages() never passed more than MAX_PAGE_ORDER to post_alloc_hook(). However, the series introducing mentioned commit changed this behavior allowing the full 1G page order to be passed. Reproducer: 1. Build the kernel with CONFIG_SPARSEMEM=y and table extensions support 2. Pass 'default_hugepagesz=1 page_owner=on' in the kernel command-line 3. Reserve one 1G page at run-time, this should crash (backtrace below) To address this issue, this commit introduces a new API for iterating through page extensions. The main iteration macro is for_each_page_ext() and it must be called with the RCU read lock taken. Here's an usage example: """ struct page_ext_iter iter; struct page_ext *page_ext; ... rcu_read_lock(); for_each_page_ext(page, 1 << order, page_ext, iter) { struct my_page_ext *obj = get_my_page_ext_obj(page_ext); ... } rcu_read_unlock(); """ The loop construct uses page_ext_iter_next() which checks to see if we have crossed sections in the iteration. In this case, page_ext_iter_next() retrieves the next page_ext object from another section. Thanks to David Hildenbrand for helping identify the root cause and providing suggestions on how to fix and optmize the solution (final implementation and bugs are all mine through). Lastly, here's the backtrace, without kasan you can get random crashes: [ 76.052526] BUG: KASAN: slab-out-of-bounds in __update_page_owner_handle+0x238/0x298 [ 76.060283] Write of size 4 at addr ffff07ff96240038 by task tee/3598 [ 76.066714] [ 76.068203] CPU: 88 UID: 0 PID: 3598 Comm: tee Kdump: loaded Not tainted 6.13.0-rep1 #3 [ 76.076202] Hardware name: WIWYNN Mt.Jade Server System B81.030Z1.0007/Mt.Jade Motherboard, BIOS 2.10.20220810 (SCP: 2.10.20220810) 2022/08/10 [ 76.088972] Call trace: [ 76.091411] show_stack+0x20/0x38 (C) [ 76.095073] dump_stack_lvl+0x80/0xf8 [ 76.098733] print_address_description.constprop.0+0x88/0x398 [ 76.104476] print_report+0xa8/0x278 [ 76.108041] kasan_report+0xa8/0xf8 [ 76.111520] __asan_report_store4_noabort+0x20/0x30 [ 76.116391] __update_page_owner_handle+0x238/0x298 [ 76.121259] __set_page_owner+0xdc/0x140 [ 76.125173] post_alloc_hook+0x190/0x1d8 [ 76.129090] alloc_contig_range_noprof+0x54c/0x890 [ 76.133874] alloc_contig_pages_noprof+0x35c/0x4a8 [ 76.138656] alloc_gigantic_folio.isra.0+0x2c0/0x368 [ 76.143616] only_alloc_fresh_hugetlb_folio.isra.0+0x24/0x150 [ 76.149353] alloc_pool_huge_folio+0x11c/0x1f8 [ 76.153787] set_max_huge_pages+0x364/0xca8 [ 76.157961] __nr_hugepages_store_common+0xb0/0x1a0 [ 76.162829] nr_hugepages_store+0x108/0x118 [ 76.167003] kobj_attr_store+0x3c/0x70 [ 76.170745] sysfs_kf_write+0xfc/0x188 [ 76.174492] kernfs_fop_write_iter+0x274/0x3e0 [ 76.178927] vfs_write+0x64c/0x8e0 [ 76.182323] ksys_write+0xf8/0x1f0 [ 76.185716] __arm64_sys_write+0x74/0xb0 [ 76.189630] invoke_syscall.constprop.0+0xd8/0x1e0 [ 76.194412] do_el0_svc+0x164/0x1e0 [ 76.197891] el0_svc+0x40/0xe0 [ 76.200939] el0t_64_sync_handler+0x144/0x168 [ 76.205287] el0t_64_sync+0x1ac/0x1b0 Link: https://lkml.kernel.org/r/cover.1741301089.git.luizcap@redhat.com Link: https://lkml.kernel.org/r/a45893880b7e1601082d39d2c5c8b50bcc096305.1741301089.git.luizcap@redhat.com Fixes: cf54f310d0d3 ("mm/hugetlb: use __GFP_COMP for gigantic folios") Signed-off-by: Luiz Capitulino <luizcap@redhat.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Luiz Capitulino <luizcap@redhat.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/damon: remove damon_operations->reset_aggregatedSeongJae Park
The operations layer hook was introduced to let operations set do any aggregation data reset if needed. But it is not really be used now. Remove it. Link: https://lkml.kernel.org/r/20250306175908.66300-14-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/damon: remove damon_callback->before_damos_applySeongJae Park
The hook was introduced to let DAMON kernel API users access DAMOS schemes-eligible regions in a safe way. Now it is no more used by anyone, and the functionality is provided in a better way by damos_walk(). Remove it. Link: https://lkml.kernel.org/r/20250306175908.66300-13-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/damon: remove damon_callback->after_samplingSeongJae Park
The callback was used by DAMON sysfs interface for reading DAMON internal data. But it is no more being used, and damon_call() can do similar works in a better way. Remove it. Link: https://lkml.kernel.org/r/20250306175908.66300-12-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/damon: remove ->before_start of damon_callbackSeongJae Park
The function pointer field was added to be used as a place to do some initialization works just before DAMON starts working. However, nobody is using it now. Remove it. Link: https://lkml.kernel.org/r/20250306175908.66300-11-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/damon: remove damon_callback->privateSeongJae Park
The field was added to let users keep their personal data to use inside of the callbacks. However, no one is actively using that now. Remove it. Link: https://lkml.kernel.org/r/20250306175908.66300-10-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17arch, mm: make releasing of memory to page allocator more explicitMike Rapoport (Microsoft)
The point where the memory is released from memblock to the buddy allocator is hidden inside arch-specific mem_init()s and the call to memblock_free_all() is needlessly duplicated in every artiste cure and after introduction of arch_mm_preinit() hook, mem_init() implementation on many architecture only contains the call to memblock_free_all(). Pull memblock_free_all() call into mm_core_init() and drop mem_init() on relevant architectures to make it more explicit where the free memory is released from memblock to the buddy allocator and to reduce code duplication in architecture specific code. Link: https://lkml.kernel.org/r/20250313135003.836600-14-rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> [x86] Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k] Tested-by: Mark Brown <broonie@kernel.org> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Andreas Larsson <andreas@gaisler.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Betkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Dinh Nguyen <dinguyen@kernel.org> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Guo Ren (csky) <guoren@kernel.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiaxun Yang <jiaxun.yang@flygoat.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Madhavan Srinivasan <maddy@linux.ibm.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Richard Weinberger <richard@nod.at> Cc: Russel King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vineet Gupta <vgupta@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17arch, mm: introduce arch_mm_preinitMike Rapoport (Microsoft)
Currently, implementation of mem_init() in every architecture consists of one or more of the following: * initializations that must run before page allocator is active, for instance swiotlb_init() * a call to memblock_free_all() to release all the memory to the buddy allocator * initializations that must run after page allocator is ready and there is no arch-specific hook other than mem_init() for that, like for example register_page_bootmem_info() in x86 and sparc64 or simple setting of mem_init_done = 1 in several architectures * a bunch of semi-related stuff that apparently had no better place to live, for example a ton of BUILD_BUG_ON()s in parisc. Introduce arch_mm_preinit() that will be the first thing called from mm_core_init(). On architectures that have initializations that must happen before the page allocator is ready, move those into arch_mm_preinit() along with the code that does not depend on ordering with page allocator setup. On several architectures this results in reduction of mem_init() to a single call to memblock_free_all() that allows its consolidation next. Link: https://lkml.kernel.org/r/20250313135003.836600-13-rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> [x86] Tested-by: Mark Brown <broonie@kernel.org> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Andreas Larsson <andreas@gaisler.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Betkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Dinh Nguyen <dinguyen@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Guo Ren (csky) <guoren@kernel.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiaxun Yang <jiaxun.yang@flygoat.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Madhavan Srinivasan <maddy@linux.ibm.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Richard Weinberger <richard@nod.at> Cc: Russel King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vineet Gupta <vgupta@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17arch, mm: streamline HIGHMEM freeingMike Rapoport (Microsoft)
All architectures that support HIGHMEM have their code that frees high memory pages to the buddy allocator while __free_memory_core() is limited to freeing only low memory. There is no actual reason for that. The memory map is completely ready by the time memblock_free_all() is called and high pages can be released to the buddy allocator along with low memory. Remove low memory limit from __free_memory_core() and drop per-architecture code that frees high memory pages. Link: https://lkml.kernel.org/r/20250313135003.836600-12-rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> [x86] Tested-by: Mark Brown <broonie@kernel.org> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Andreas Larsson <andreas@gaisler.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Betkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Dinh Nguyen <dinguyen@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Guo Ren (csky) <guoren@kernel.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiaxun Yang <jiaxun.yang@flygoat.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Madhavan Srinivasan <maddy@linux.ibm.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Richard Weinberger <richard@nod.at> Cc: Russel King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vineet Gupta <vgupta@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17arch, mm: set max_mapnr when allocating memory map for FLATMEMMike Rapoport (Microsoft)
max_mapnr is essentially the size of the memory map for systems that use FLATMEM. There is no reason to calculate it in each and every architecture when it's anyway calculated in alloc_node_mem_map(). Drop setting of max_mapnr from architecture code and set it once in alloc_node_mem_map(). While on it, move definition of mem_map and max_mapnr to mm/mm_init.c so there won't be two copies for MMU and !MMU variants. Link: https://lkml.kernel.org/r/20250313135003.836600-10-rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> [x86] Tested-by: Mark Brown <broonie@kernel.org> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Andreas Larsson <andreas@gaisler.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Betkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Dinh Nguyen <dinguyen@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Guo Ren (csky) <guoren@kernel.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiaxun Yang <jiaxun.yang@flygoat.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Madhavan Srinivasan <maddy@linux.ibm.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Richard Weinberger <richard@nod.at> Cc: Russel King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vineet Gupta <vgupta@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17page_io: zswap: do not crash the kernel on decompression failureNhat Pham
Currently, we crash the kernel when a decompression failure occurs in zswap (either because of memory corruption, or a bug in the compression algorithm). This is overkill. We should only SIGBUS the unfortunate process asking for the zswap entry on zswap load, and skip the corrupted entry in zswap writeback. See [1] for a recent upstream discussion about this. The zswap writeback case is relatively straightforward to fix. For the zswap_load() case, we change the return behavior: * Return 0 on success. * Return -ENOENT (with the folio locked) if zswap does not own the swapped out content. * Return -EIO if zswap owns the swapped out content, but encounters a decompression failure for some reasons. The folio will be unlocked, but not be marked up-to-date, which will eventually cause the process requesting the page to SIGBUS (see the handling of not-up-to-date folio in do_swap_page() in mm/memory.c), without crashing the kernel. * Return -EINVAL if we encounter a large folio, as large folio should not be swapped in while zswap is being used. Similar to the -EIO case, we also unlock the folio but do not mark it as up-to-date to SIGBUS the faulting process. As a side effect, we require one extra zswap tree traversal in the load and writeback paths. Quick benchmarking on a kernel build test shows no performance difference: With the new scheme: real: mean: 125.1s, stdev: 0.12s user: mean: 3265.23s, stdev: 9.62s sys: mean: 2156.41s, stdev: 13.98s The old scheme: real: mean: 125.78s, stdev: 0.45s user: mean: 3287.18s, stdev: 5.95s sys: mean: 2177.08s, stdev: 26.52s [nphamcs@gmail.com: fix documentation of zswap_load()] Link: https://lkml.kernel.org/r/20250306222453.1269456-1-nphamcs@gmail.com Link: https://lore.kernel.org/all/ZsiLElTykamcYZ6J@casper.infradead.org/ [1] Link: https://lkml.kernel.org/r/20250306205011.784787-1-nphamcs@gmail.com Signed-off-by: Nhat Pham <nphamcs@gmail.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Suggested-by: Yosry Ahmed <yosry.ahmed@linux.dev> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/damon/core: expose damos_filter_for_ops() to DAMON kernel API callersSeongJae Park
damos_filter_for_ops() can be useful to avoid putting wrong type of filters in wrong place. Make it be exposed to DAMON kernel API callers. Link: https://lkml.kernel.org/r/20250305222733.59089-5-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm: stop maintaining the per-page mapcount of large folios ↵David Hildenbrand
(CONFIG_NO_PAGE_MAPCOUNT) Everything is in place to stop using the per-page mapcounts in large folios: the mapcount of tail pages will always be logically 0 (-1 value), just like it currently is for hugetlb folios already, and the page mapcount of the head page is either 0 (-1 value) or contains a page type (e.g., hugetlb). Maintaining _nr_pages_mapped without per-page mapcounts is impossible, so that one also has to go with CONFIG_NO_PAGE_MAPCOUNT. There are two remaining implications: (1) Per-node, per-cgroup and per-lruvec stats of "NR_ANON_MAPPED" ("mapped anonymous memory") and "NR_FILE_MAPPED" ("mapped file memory"): As soon as any page of the folio is mapped -- folio_mapped() -- we now account the complete folio as mapped. Once the last page is unmapped -- !folio_mapped() -- we account the complete folio as unmapped. This implies that ... * "AnonPages" and "Mapped" in /proc/meminfo and /sys/devices/system/node/*/meminfo * cgroup v2: "anon" and "file_mapped" in "memory.stat" and "memory.numa_stat" * cgroup v1: "rss" and "mapped_file" in "memory.stat" and "memory.numa_stat ... can now appear higher than before. But note that these folios do consume that memory, simply not all pages are actually currently mapped. It's worth nothing that other accounting in the kernel (esp. cgroup charging on allocation) is not affected by this change. [why oh why is "anon" called "rss" in cgroup v1] (2) Detecting partial mappings Detecting whether anon THPs are partially mapped gets a bit more unreliable. As long as a single MM maps such a large folio ("exclusively mapped"), we can reliably detect it. Especially before fork() / after a short-lived child process quit, we will detect partial mappings reliably, which is the common case. In essence, if the average per-page mapcount in an anon THP is < 1, we know for sure that we have a partial mapping. However, as soon as multiple MMs are involved, we might miss detecting partial mappings: this might be relevant with long-lived child processes. If we have a fully-mapped anon folio before fork(), once our child processes and our parent all unmap (zap/COW) the same pages (but not the complete folio), we might not detect the partial mapping. However, once the child processes quit we would detect the partial mapping. How relevant this case is in practice remains to be seen. Swapout/migration will likely mitigate this. In the future, RMAP walkers could check for that for that case (e.g., when collecting access bits during reclaim) and simply flag them for deferred-splitting. Link: https://lkml.kernel.org/r/20250303163014.1128035-21-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Andy Lutomirks^H^Hski <luto@kernel.org> Cc: Borislav Betkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lance Yang <ioworker0@gmail.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Matthew Wilcow (Oracle) <willy@infradead.org> Cc: Michal Koutn <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: tejun heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zefan Li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm: convert folio_likely_mapped_shared() to folio_maybe_mapped_shared()David Hildenbrand
Let's reuse our new MM ownership tracking infrastructure for large folios to make folio_likely_mapped_shared() never return false negatives -- never indicating "not mapped shared" although the folio *is* mapped shared. With that, we can rename it to folio_maybe_mapped_shared() and get rid of the dependency on the mapcount of the first folio page. The semantics are now arguably clearer: no mixture of "false negatives" and "false positives", only the remaining possibility for "false positives". Thoroughly document the new semantics. We might now detect that a large folio is "maybe mapped shared" although it *no longer* is -- but once was. Now, if more than two MMs mapped a folio at the same time, and the MM mapping the folio exclusively at the end is not one tracked in the two folio MM slots, we will detect the folio as "maybe mapped shared". For anonymous folios, usually (except weird corner cases) all PTEs that target a "maybe mapped shared" folio are R/O. As soon as a child process would write to them (iow, actively use them), we would CoW and effectively replace these PTEs. Most cases (below) are not expected to really matter with large anonymous folios for this reason. Most importantly, there will be no change at all for: * small folios * hugetlb folios * PMD-mapped PMD-sized THPs (single mapping) This change has the potential to affect existing callers of folio_likely_mapped_shared() -> folio_maybe_mapped_shared(): (1) fs/proc/task_mmu.c: no change (hugetlb) (2) khugepaged counts PTEs that target shared folios towards max_ptes_shared (default: HPAGE_PMD_NR / 2), meaning we could skip a collapse where we would have previously collapsed. This only applies to anonymous folios and is not expected to matter in practice. Worth noting that this change sorts out case (A) documented in commit 1bafe96e89f0 ("mm/khugepaged: replace page_mapcount() check by folio_likely_mapped_shared()") by removing the possibility for "false negatives". (3) MADV_COLD / MADV_PAGEOUT / MADV_FREE will not try splitting PTE-mapped THPs that are considered shared but not fully covered by the requested range, consequently not processing them. PMD-mapped PMD-sized THP are not affected, or when all PTEs are covered. These functions are usually only called on anon/file folios that are exclusively mapped most of the time (no other file mappings or no fork()), so the "false negatives" are not expected to matter in practice. (4) mbind() / migrate_pages() / move_pages() will refuse to migrate shared folios unless MPOL_MF_MOVE_ALL is effective (requires CAP_SYS_NICE). We will now reject some folios that could be migrated. Similar to (3), especially with MPOL_MF_MOVE_ALL, so this is not expected to matter in practice. Note that cpuset_migrate_mm_workfn() calls do_migrate_pages() with MPOL_MF_MOVE_ALL. (5) NUMA hinting mm/migrate.c:migrate_misplaced_folio_prepare() will skip file folios that are probably shared libraries (-> "mapped shared" and executable). This check would have detected it as a shared library at some point (at least 3 MMs mapping it), so detecting it afterwards does not sound wrong (still a shared library). Not expected to matter. mm/memory.c:numa_migrate_check() will indicate TNF_SHARED in MAP_SHARED file mappings when encountering a shared folio. Similar reasoning, not expected to matter. mm/mprotect.c:change_pte_range() will skip folios detected as shared in CoW mappings. Similarly, this is not expected to matter in practice, but if it would ever be a problem we could relax that check a bit (e.g., basing it on the average page-mapcount in a folio), because it was only an optimization when many (e.g., 288) processes were mapping the same folios -- see commit 859d4adc3415 ("mm: numa: do not trap faults on shared data section pages.") (6) mm/rmap.c:folio_referenced_one() will skip exclusive swapbacked folios in dying processes. Applies to anonymous folios only. Without "false negatives", we'll now skip all actually shared ones. Skipping ones that are actually exclusive won't really matter, it's a pure optimization, and is not expected to matter in practice. In theory, one can detect the problematic scenario: folio_mapcount() > 0 and no folio MM slot is occupied ("state unknown"). One could reset the MM slots while doing an rmap walk, which migration / folio split already do when setting everything up. Further, when batching PTEs we might naturally learn about a owner (e.g., folio_mapcount() == nr_ptes) and could update the owner. However, we'll defer that until the scenarios where it would really matter are clear. Link: https://lkml.kernel.org/r/20250303163014.1128035-15-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Andy Lutomirks^H^Hski <luto@kernel.org> Cc: Borislav Betkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lance Yang <ioworker0@gmail.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Matthew Wilcow (Oracle) <willy@infradead.org> Cc: Michal Koutn <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: tejun heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zefan Li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17mm/rmap: basic MM owner tracking for large folios (!hugetlb)David Hildenbrand
For small folios, we traditionally use the mapcount to decide whether it was "certainly mapped exclusively" by a single MM (mapcount == 1) or whether it "maybe mapped shared" by multiple MMs (mapcount > 1). For PMD-sized folios that were PMD-mapped, we were able to use a similar mechanism (single PMD mapping), but for PTE-mapped folios and in the future folios that span multiple PMDs, this does not work. So we need a different mechanism to handle large folios. Let's add a new mechanism to detect whether a large folio is "certainly mapped exclusively", or whether it is "maybe mapped shared". We'll use this information next to optimize CoW reuse for PTE-mapped anonymous THP, and to convert folio_likely_mapped_shared() to folio_maybe_mapped_shared(), independent of per-page mapcounts. For each large folio, we'll have two slots, whereby a slot stores: (1) an MM id: unique id assigned to each MM (2) a per-MM mapcount If a slot is unoccupied, it can be taken by the next MM that maps folio page. In addition, we'll remember the current state -- "mapped exclusively" vs. "maybe mapped shared" -- and use a bit spinlock to sync on updates and to reduce the total number of atomic accesses on updates. In the future, it might be possible to squeeze a proper spinlock into "struct folio". For now, keep it simple, as we require the whole thing with THP only, that is incompatible with RT. As we have to squeeze this information into the "struct folio" of even folios of order-1 (2 pages), and we generally want to reduce the required metadata, we'll assign each MM a unique ID that can fit into an int. In total, we can squeeze everything into 4x int (2x long) on 64bit. 32bit support is a bit challenging, because we only have 2x long == 2x int in order-1 folios. But we can make it work for now, because we neither expect many MMs nor very large folios on 32bit. We will reliably detect folios as "mapped exclusively" vs. "mapped shared" as long as only two MMs map pages of a folio at one point in time -- for example with fork() and short-lived child processes, or with apps that hand over state from one instance to another. As soon as three MMs are involved at the same time, we might detect "maybe mapped shared" although the folio is "mapped exclusively". Example 1: (1) App1 faults in a (shmem/file-backed) folio page -> Tracked as MM0 (2) App2 faults in a folio page -> Tracked as MM1 (4) App1 unmaps all folio pages -> We will detect "mapped exclusively". Example 2: (1) App1 faults in a (shmem/file-backed) folio page -> Tracked as MM0 (2) App2 faults in a folio page -> Tracked as MM1 (3) App3 faults in a folio page -> No slot available, tracked as "unknown" (4) App1 and App2 unmap all folio pages -> We will detect "maybe mapped shared". Make use of __always_inline to keep possible performance degradation when (un)mapping large folios to a minimum. Note: by squeezing the two flags into the "unsigned long" that stores the MM ids, we can use non-atomic __bit_spin_unlock() and non-atomic setting/clearing of the "maybe mapped shared" bit, effectively not adding any new atomics on the hot path when updating the large mapcount + new metadata, which further helps reduce the runtime overhead in micro-benchmarks. Link: https://lkml.kernel.org/r/20250303163014.1128035-13-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Andy Lutomirks^H^Hski <luto@kernel.org> Cc: Borislav Betkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lance Yang <ioworker0@gmail.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Matthew Wilcow (Oracle) <willy@infradead.org> Cc: Michal Koutn <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: tejun heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zefan Li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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