diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 21 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/hugetlbpage.rst | 11 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/memory-hotplug.rst | 13 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/pagemap.rst | 2 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/userfaultfd.rst | 3 | ||||
| -rw-r--r-- | Documentation/core-api/kernel-api.rst | 7 | ||||
| -rw-r--r-- | Documentation/filesystems/proc.rst | 48 | ||||
| -rw-r--r-- | Documentation/vm/hmm.rst | 19 | ||||
| -rw-r--r-- | Documentation/vm/unevictable-lru.rst | 33 |
9 files changed, 122 insertions, 35 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 0315407f5f57..13f13fdd4731 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1594,6 +1594,23 @@ Documentation/admin-guide/mm/hugetlbpage.rst. Format: size[KMG] + hugetlb_free_vmemmap= + [KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP + enabled. + Allows heavy hugetlb users to free up some more + memory (6 * PAGE_SIZE for each 2MB hugetlb page). + Format: { on | off (default) } + + on: enable the feature + off: disable the feature + + Built with CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON=y, + the default is on. + + This is not compatible with memory_hotplug.memmap_on_memory. + If both parameters are enabled, hugetlb_free_vmemmap takes + precedence over memory_hotplug.memmap_on_memory. + hung_task_panic= [KNL] Should the hung task detector generate panics. Format: 0 | 1 @@ -2860,6 +2877,10 @@ Note that even when enabled, there are a few cases where the feature is not effective. + This is not compatible with hugetlb_free_vmemmap. If + both parameters are enabled, hugetlb_free_vmemmap takes + precedence over memory_hotplug.memmap_on_memory. + memtest= [KNL,X86,ARM,PPC,RISCV] Enable memtest Format: <integer> default : 0 <disable> diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst index f7b1c7462991..8abaeb144e44 100644 --- a/Documentation/admin-guide/mm/hugetlbpage.rst +++ b/Documentation/admin-guide/mm/hugetlbpage.rst @@ -60,6 +60,10 @@ HugePages_Surp the pool above the value in ``/proc/sys/vm/nr_hugepages``. The maximum number of surplus huge pages is controlled by ``/proc/sys/vm/nr_overcommit_hugepages``. + Note: When the feature of freeing unused vmemmap pages associated + with each hugetlb page is enabled, the number of surplus huge pages + may be temporarily larger than the maximum number of surplus huge + pages when the system is under memory pressure. Hugepagesize is the default hugepage size (in Kb). Hugetlb @@ -80,6 +84,10 @@ returned to the huge page pool when freed by a task. A user with root privileges can dynamically allocate more or free some persistent huge pages by increasing or decreasing the value of ``nr_hugepages``. +Note: When the feature of freeing unused vmemmap pages associated with each +hugetlb page is enabled, we can fail to free the huge pages triggered by +the user when ths system is under memory pressure. Please try again later. + Pages that are used as huge pages are reserved inside the kernel and cannot be used for other purposes. Huge pages cannot be swapped out under memory pressure. @@ -145,6 +153,9 @@ default_hugepagesz will all result in 256 2M huge pages being allocated. Valid default huge page size is architecture dependent. +hugetlb_free_vmemmap + When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing + unused vmemmap pages associated with each HugeTLB page. When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages`` indicates the current number of pre-allocated huge pages of the default size. diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst index 05d51d2d8beb..c6bae2d77160 100644 --- a/Documentation/admin-guide/mm/memory-hotplug.rst +++ b/Documentation/admin-guide/mm/memory-hotplug.rst @@ -357,6 +357,19 @@ creates ZONE_MOVABLE as following. Unfortunately, there is no information to show which memory block belongs to ZONE_MOVABLE. This is TBD. + Memory offlining can fail when dissolving a free huge page on ZONE_MOVABLE + and the feature of freeing unused vmemmap pages associated with each hugetlb + page is enabled. + + This can happen when we have plenty of ZONE_MOVABLE memory, but not enough + kernel memory to allocate vmemmmap pages. We may even be able to migrate + huge page contents, but will not be able to dissolve the source huge page. + This will prevent an offline operation and is unfortunate as memory offlining + is expected to succeed on movable zones. Users that depend on memory hotplug + to succeed for movable zones should carefully consider whether the memory + savings gained from this feature are worth the risk of possibly not being + able to offline memory in certain situations. + .. note:: Techniques that rely on long-term pinnings of memory (especially, RDMA and vfio) are fundamentally problematic with ZONE_MOVABLE and, therefore, memory diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst index 340a5aee9b80..fb578fbbb76c 100644 --- a/Documentation/admin-guide/mm/pagemap.rst +++ b/Documentation/admin-guide/mm/pagemap.rst @@ -21,6 +21,8 @@ There are four components to pagemap: * Bit 55 pte is soft-dirty (see :ref:`Documentation/admin-guide/mm/soft-dirty.rst <soft_dirty>`) * Bit 56 page exclusively mapped (since 4.2) + * Bit 57 pte is uffd-wp write-protected (since 5.13) (see + :ref:`Documentation/admin-guide/mm/userfaultfd.rst <userfaultfd>`) * Bits 57-60 zero * Bit 61 page is file-page or shared-anon (since 3.5) * Bit 62 page swapped diff --git a/Documentation/admin-guide/mm/userfaultfd.rst b/Documentation/admin-guide/mm/userfaultfd.rst index 3aa38e8b8361..6528036093e1 100644 --- a/Documentation/admin-guide/mm/userfaultfd.rst +++ b/Documentation/admin-guide/mm/userfaultfd.rst @@ -77,7 +77,8 @@ events, except page fault notifications, may be generated: - ``UFFD_FEATURE_MINOR_HUGETLBFS`` indicates that the kernel supports ``UFFDIO_REGISTER_MODE_MINOR`` registration for hugetlbfs virtual memory - areas. + areas. ``UFFD_FEATURE_MINOR_SHMEM`` is the analogous feature indicating + support for shmem virtual memory areas. The userland application should set the feature flags it intends to use when invoking the ``UFFDIO_API`` ioctl, to request that those features be diff --git a/Documentation/core-api/kernel-api.rst b/Documentation/core-api/kernel-api.rst index 741aa37dc181..2a7444e3a4c2 100644 --- a/Documentation/core-api/kernel-api.rst +++ b/Documentation/core-api/kernel-api.rst @@ -24,11 +24,8 @@ String Conversions .. kernel-doc:: lib/vsprintf.c :export: -.. kernel-doc:: include/linux/kernel.h - :functions: kstrtol - -.. kernel-doc:: include/linux/kernel.h - :functions: kstrtoul +.. kernel-doc:: include/linux/kstrtox.h + :functions: kstrtol kstrtoul .. kernel-doc:: lib/kstrtox.c :export: diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 81bfe3c800cc..042c418f4090 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -933,8 +933,15 @@ meminfo ~~~~~~~ Provides information about distribution and utilization of memory. This -varies by architecture and compile options. The following is from a -16GB PIII, which has highmem enabled. You may not have all of these fields. +varies by architecture and compile options. Some of the counters reported +here overlap. The memory reported by the non overlapping counters may not +add up to the overall memory usage and the difference for some workloads +can be substantial. In many cases there are other means to find out +additional memory using subsystem specific interfaces, for instance +/proc/net/sockstat for TCP memory allocations. + +The following is from a 16GB PIII, which has highmem enabled. +You may not have all of these fields. :: @@ -1913,18 +1920,20 @@ if precise results are needed. 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file --------------------------------------------------------------- This file provides information associated with an opened file. The regular -files have at least three fields -- 'pos', 'flags' and 'mnt_id'. The 'pos' -represents the current offset of the opened file in decimal form [see lseek(2) -for details], 'flags' denotes the octal O_xxx mask the file has been -created with [see open(2) for details] and 'mnt_id' represents mount ID of -the file system containing the opened file [see 3.5 /proc/<pid>/mountinfo -for details]. +files have at least four fields -- 'pos', 'flags', 'mnt_id' and 'ino'. +The 'pos' represents the current offset of the opened file in decimal +form [see lseek(2) for details], 'flags' denotes the octal O_xxx mask the +file has been created with [see open(2) for details] and 'mnt_id' represents +mount ID of the file system containing the opened file [see 3.5 +/proc/<pid>/mountinfo for details]. 'ino' represents the inode number of +the file. A typical output is:: pos: 0 flags: 0100002 mnt_id: 19 + ino: 63107 All locks associated with a file descriptor are shown in its fdinfo too:: @@ -1941,6 +1950,7 @@ Eventfd files pos: 0 flags: 04002 mnt_id: 9 + ino: 63107 eventfd-count: 5a where 'eventfd-count' is hex value of a counter. @@ -1953,6 +1963,7 @@ Signalfd files pos: 0 flags: 04002 mnt_id: 9 + ino: 63107 sigmask: 0000000000000200 where 'sigmask' is hex value of the signal mask associated @@ -1966,6 +1977,7 @@ Epoll files pos: 0 flags: 02 mnt_id: 9 + ino: 63107 tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7 where 'tfd' is a target file descriptor number in decimal form, @@ -1982,6 +1994,8 @@ For inotify files the format is the following:: pos: 0 flags: 02000000 + mnt_id: 9 + ino: 63107 inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d where 'wd' is a watch descriptor in decimal form, i.e. a target file @@ -2004,6 +2018,7 @@ For fanotify files the format is:: pos: 0 flags: 02 mnt_id: 9 + ino: 63107 fanotify flags:10 event-flags:0 fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003 fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4 @@ -2028,6 +2043,7 @@ Timerfd files pos: 0 flags: 02 mnt_id: 9 + ino: 63107 clockid: 0 ticks: 0 settime flags: 01 @@ -2042,6 +2058,22 @@ details]. 'it_value' is remaining time until the timer expiration. with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value' still exhibits timer's remaining time. +DMA Buffer files +~~~~~~~~~~~~~~~~ + +:: + + pos: 0 + flags: 04002 + mnt_id: 9 + ino: 63107 + size: 32768 + count: 2 + exp_name: system-heap + +where 'size' is the size of the DMA buffer in bytes. 'count' is the file count of +the DMA buffer file. 'exp_name' is the name of the DMA buffer exporter. + 3.9 /proc/<pid>/map_files - Information about memory mapped files --------------------------------------------------------------------- This directory contains symbolic links which represent memory mapped files diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst index 09e28507f5b2..a14c2938e7af 100644 --- a/Documentation/vm/hmm.rst +++ b/Documentation/vm/hmm.rst @@ -332,7 +332,7 @@ between device driver specific code and shared common code: walks to fill in the ``args->src`` array with PFNs to be migrated. The ``invalidate_range_start()`` callback is passed a ``struct mmu_notifier_range`` with the ``event`` field set to - ``MMU_NOTIFY_MIGRATE`` and the ``migrate_pgmap_owner`` field set to + ``MMU_NOTIFY_MIGRATE`` and the ``owner`` field set to the ``args->pgmap_owner`` field passed to migrate_vma_setup(). This is allows the device driver to skip the invalidation callback and only invalidate device private MMU mappings that are actually migrating. @@ -405,6 +405,23 @@ between device driver specific code and shared common code: The lock can now be released. +Exclusive access memory +======================= + +Some devices have features such as atomic PTE bits that can be used to implement +atomic access to system memory. To support atomic operations to a shared virtual +memory page such a device needs access to that page which is exclusive of any +userspace access from the CPU. The ``make_device_exclusive_range()`` function +can be used to make a memory range inaccessible from userspace. + +This replaces all mappings for pages in the given range with special swap +entries. Any attempt to access the swap entry results in a fault which is +resovled by replacing the entry with the original mapping. A driver gets +notified that the mapping has been changed by MMU notifiers, after which point +it will no longer have exclusive access to the page. Exclusive access is +guranteed to last until the driver drops the page lock and page reference, at +which point any CPU faults on the page may proceed as described. + Memory cgroup (memcg) and rss accounting ======================================== diff --git a/Documentation/vm/unevictable-lru.rst b/Documentation/vm/unevictable-lru.rst index 0e1490524f53..eae3af17f2d9 100644 --- a/Documentation/vm/unevictable-lru.rst +++ b/Documentation/vm/unevictable-lru.rst @@ -389,14 +389,14 @@ mlocked, munlock_vma_page() updates that zone statistics for the number of mlocked pages. Note, however, that at this point we haven't checked whether the page is mapped by other VM_LOCKED VMAs. -We can't call try_to_munlock(), the function that walks the reverse map to +We can't call page_mlock(), the function that walks the reverse map to check for other VM_LOCKED VMAs, without first isolating the page from the LRU. -try_to_munlock() is a variant of try_to_unmap() and thus requires that the page +page_mlock() is a variant of try_to_unmap() and thus requires that the page not be on an LRU list [more on these below]. However, the call to -isolate_lru_page() could fail, in which case we couldn't try_to_munlock(). So, +isolate_lru_page() could fail, in which case we can't call page_mlock(). So, we go ahead and clear PG_mlocked up front, as this might be the only chance we -have. If we can successfully isolate the page, we go ahead and -try_to_munlock(), which will restore the PG_mlocked flag and update the zone +have. If we can successfully isolate the page, we go ahead and call +page_mlock(), which will restore the PG_mlocked flag and update the zone page statistics if it finds another VMA holding the page mlocked. If we fail to isolate the page, we'll have left a potentially mlocked page on the LRU. This is fine, because we'll catch it later if and if vmscan tries to reclaim @@ -545,31 +545,24 @@ munlock or munmap system calls, mm teardown (munlock_vma_pages_all), reclaim, holepunching, and truncation of file pages and their anonymous COWed pages. -try_to_munlock() Reverse Map Scan +page_mlock() Reverse Map Scan --------------------------------- -.. warning:: - [!] TODO/FIXME: a better name might be page_mlocked() - analogous to the - page_referenced() reverse map walker. - When munlock_vma_page() [see section :ref:`munlock()/munlockall() System Call Handling <munlock_munlockall_handling>` above] tries to munlock a page, it needs to determine whether or not the page is mapped by any VM_LOCKED VMA without actually attempting to unmap all PTEs from the page. For this purpose, the unevictable/mlock infrastructure -introduced a variant of try_to_unmap() called try_to_munlock(). +introduced a variant of try_to_unmap() called page_mlock(). -try_to_munlock() calls the same functions as try_to_unmap() for anonymous and -mapped file and KSM pages with a flag argument specifying unlock versus unmap -processing. Again, these functions walk the respective reverse maps looking -for VM_LOCKED VMAs. When such a VMA is found, as in the try_to_unmap() case, -the functions mlock the page via mlock_vma_page() and return SWAP_MLOCK. This -undoes the pre-clearing of the page's PG_mlocked done by munlock_vma_page. +page_mlock() walks the respective reverse maps looking for VM_LOCKED VMAs. When +such a VMA is found the page is mlocked via mlock_vma_page(). This undoes the +pre-clearing of the page's PG_mlocked done by munlock_vma_page. -Note that try_to_munlock()'s reverse map walk must visit every VMA in a page's +Note that page_mlock()'s reverse map walk must visit every VMA in a page's reverse map to determine that a page is NOT mapped into any VM_LOCKED VMA. However, the scan can terminate when it encounters a VM_LOCKED VMA. -Although try_to_munlock() might be called a great many times when munlocking a +Although page_mlock() might be called a great many times when munlocking a large region or tearing down a large address space that has been mlocked via mlockall(), overall this is a fairly rare event. @@ -602,7 +595,7 @@ inactive lists to the appropriate node's unevictable list. shrink_inactive_list() should only see SHM_LOCK'd pages that became SHM_LOCK'd after shrink_active_list() had moved them to the inactive list, or pages mapped into VM_LOCKED VMAs that munlock_vma_page() couldn't isolate from the LRU to -recheck via try_to_munlock(). shrink_inactive_list() won't notice the latter, +recheck via page_mlock(). shrink_inactive_list() won't notice the latter, but will pass on to shrink_page_list(). shrink_page_list() again culls obviously unevictable pages that it could |