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2012-03-28Merge branch 'akpm' (Andrew's patch-bomb)Linus Torvalds
Merge third batch of patches from Andrew Morton: - Some MM stragglers - core SMP library cleanups (on_each_cpu_mask) - Some IPI optimisations - kexec - kdump - IPMI - the radix-tree iterator work - various other misc bits. "That'll do for -rc1. I still have ~10 patches for 3.4, will send those along when they've baked a little more." * emailed from Andrew Morton <akpm@linux-foundation.org>: (35 commits) backlight: fix typo in tosa_lcd.c crc32: add help text for the algorithm select option mm: move hugepage test examples to tools/testing/selftests/vm mm: move slabinfo.c to tools/vm mm: move page-types.c from Documentation to tools/vm selftests/Makefile: make `run_tests' depend on `all' selftests: launch individual selftests from the main Makefile radix-tree: use iterators in find_get_pages* functions radix-tree: rewrite gang lookup using iterator radix-tree: introduce bit-optimized iterator fs/proc/namespaces.c: prevent crash when ns_entries[] is empty nbd: rename the nbd_device variable from lo to nbd pidns: add reboot_pid_ns() to handle the reboot syscall sysctl: use bitmap library functions ipmi: use locks on watchdog timeout set on reboot ipmi: simplify locking ipmi: fix message handling during panics ipmi: use a tasklet for handling received messages ipmi: increase KCS timeouts ipmi: decrease the IPMI message transaction time in interrupt mode ...
2012-03-28radix-tree: use iterators in find_get_pages* functionsKonstantin Khlebnikov
Replace radix_tree_gang_lookup_slot() and radix_tree_gang_lookup_tag_slot() in page-cache lookup functions with brand-new radix-tree direct iterating. This avoids the double-scanning and pointer copying. Iterator don't stop after nr_pages page-get fails in a row, it continue lookup till the radix-tree end. Thus we can safely remove these restart conditions. Unfortunately, old implementation didn't forbid nr_pages == 0, this corner case does not fit into new code, so the patch adds an extra check at the beginning. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Tested-by: Hugh Dickins <hughd@google.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-28mm: only IPI CPUs to drain local pages if they existGilad Ben-Yossef
Calculate a cpumask of CPUs with per-cpu pages in any zone and only send an IPI requesting CPUs to drain these pages to the buddy allocator if they actually have pages when asked to flush. This patch saves 85%+ of IPIs asking to drain per-cpu pages in case of severe memory pressure that leads to OOM since in these cases multiple, possibly concurrent, allocation requests end up in the direct reclaim code path so when the per-cpu pages end up reclaimed on first allocation failure for most of the proceeding allocation attempts until the memory pressure is off (possibly via the OOM killer) there are no per-cpu pages on most CPUs (and there can easily be hundreds of them). This also has the side effect of shortening the average latency of direct reclaim by 1 or more order of magnitude since waiting for all the CPUs to ACK the IPI takes a long time. Tested by running "hackbench 400" on a 8 CPU x86 VM and observing the difference between the number of direct reclaim attempts that end up in drain_all_pages() and those were more then 1/2 of the online CPU had any per-cpu page in them, using the vmstat counters introduced in the next patch in the series and using proc/interrupts. In the test sceanrio, this was seen to save around 3600 global IPIs after trigerring an OOM on a concurrent workload: $ cat /proc/vmstat | tail -n 2 pcp_global_drain 0 pcp_global_ipi_saved 0 $ cat /proc/interrupts | grep CAL CAL: 1 2 1 2 2 2 2 2 Function call interrupts $ hackbench 400 [OOM messages snipped] $ cat /proc/vmstat | tail -n 2 pcp_global_drain 3647 pcp_global_ipi_saved 3642 $ cat /proc/interrupts | grep CAL CAL: 6 13 6 3 3 3 1 2 7 Function call interrupts Please note that if the global drain is removed from the direct reclaim path as a patch from Mel Gorman currently suggests this should be replaced with an on_each_cpu_cond invocation. Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Pekka Enberg <penberg@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Acked-by: Michal Nazarewicz <mina86@mina86.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-28slub: only IPI CPUs that have per cpu obj to flushGilad Ben-Yossef
flush_all() is called for each kmem_cache_destroy(). So every cache being destroyed dynamically ends up sending an IPI to each CPU in the system, regardless if the cache has ever been used there. For example, if you close the Infinband ipath driver char device file, the close file ops calls kmem_cache_destroy(). So running some infiniband config tool on one a single CPU dedicated to system tasks might interrupt the rest of the 127 CPUs dedicated to some CPU intensive or latency sensitive task. I suspect there is a good chance that every line in the output of "git grep kmem_cache_destroy linux/ | grep '\->'" has a similar scenario. This patch attempts to rectify this issue by sending an IPI to flush the per cpu objects back to the free lists only to CPUs that seem to have such objects. The check which CPU to IPI is racy but we don't care since asking a CPU without per cpu objects to flush does no damage and as far as I can tell the flush_all by itself is racy against allocs on remote CPUs anyway, so if you required the flush_all to be determinstic, you had to arrange for locking regardless. Without this patch the following artificial test case: $ cd /sys/kernel/slab $ for DIR in *; do cat $DIR/alloc_calls > /dev/null; done produces 166 IPIs on an cpuset isolated CPU. With it it produces none. The code path of memory allocation failure for CPUMASK_OFFSTACK=y config was tested using fault injection framework. Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Pekka Enberg <penberg@kernel.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Sasha Levin <levinsasha928@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Avi Kivity <avi@redhat.com> Cc: Michal Nazarewicz <mina86@mina86.org> Cc: Kosaki Motohiro <kosaki.motohiro@gmail.com> Cc: Milton Miller <miltonm@bga.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-28swapon: check validity of swap_flagsHugh Dickins
Most system calls taking flags first check that the flags passed in are valid, and that helps userspace to detect when new flags are supported. But swapon never did so: start checking now, to help if we ever want to support more swap_flags in future. It's difficult to get stray bits set in an int, and swapon is not widely used, so this is most unlikely to break any userspace; but we can just revert if it turns out to do so. Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-28mm, coredump: fail allocations when coredumping instead of oom killingDavid Rientjes
The size of coredump files is limited by RLIMIT_CORE, however, allocating large amounts of memory results in three negative consequences: - the coredumping process may be chosen for oom kill and quickly deplete all memory reserves in oom conditions preventing further progress from being made or tasks from exiting, - the coredumping process may cause other processes to be oom killed without fault of their own as the result of a SIGSEGV, for example, in the coredumping process, or - the coredumping process may result in a livelock while writing to the dump file if it needs memory to allocate while other threads are in the exit path waiting on the coredumper to complete. This is fixed by implying __GFP_NORETRY in the page allocator for coredumping processes when reclaim has failed so the allocations fail and the process continues to exit. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-28mm: thp: fix up pmd_trans_unstable() locationsAndrea Arcangeli
pmd_trans_unstable() should be called before pmd_offset_map() in the locations where the mmap_sem is held for reading. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mark Salter <msalter@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-28mm for fs: add truncate_pagecache_range()Hugh Dickins
Holepunching filesystems ext4 and xfs are using truncate_inode_pages_range but forgetting to unmap pages first (ocfs2 remembers). This is not really a bug, since races already require truncate_inode_page() to handle that case once the page is locked; but it can be very inefficient if the file being punched happens to be mapped into many vmas. Provide a drop-in replacement truncate_pagecache_range() which does the unmapping pass first, handling the awkward mismatch between arguments to truncate_inode_pages_range() and arguments to unmap_mapping_range(). Note that holepunching does not unmap privately COWed pages in the range: POSIX requires that we do so when truncating, but it's hard to justify, difficult to implement without an i_size cutoff, and no filesystem is attempting to implement it. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Ben Myers <bpm@sgi.com> Cc: Alex Elder <elder@kernel.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Dave Chinner <david@fromorbit.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-28Merge branch 'slab/for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux Pull SLAB changes from Pekka Enberg: "There's the new kmalloc_array() API, minor fixes and performance improvements, but quite honestly, nothing terribly exciting." * 'slab/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux: mm: SLAB Out-of-memory diagnostics slab: introduce kmalloc_array() slub: per cpu partial statistics change slub: include include for prefetch slub: Do not hold slub_lock when calling sysfs_slab_add() slub: prefetch next freelist pointer in slab_alloc() slab, cleanup: remove unneeded return
2012-03-28Merge tag 'ext4_for_linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 Pull ext4 updates for 3.4 from Ted Ts'o: "Ext4 commits for 3.3 merge window; mostly cleanups and bug fixes The changes to export dirty_writeback_interval are from Artem's s_dirt cleanup patch series. The same is true of the change to remove the s_dirt helper functions which never got used by anyone in-tree. I've run these changes by Al Viro, and am carrying them so that Artem can more easily fix up the rest of the file systems during the next merge window. (Originally we had hopped to remove the use of s_dirt from ext4 during this merge window, but his patches had some bugs, so I ultimately ended dropping them from the ext4 tree.)" * tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (66 commits) vfs: remove unused superblock helpers mm: export dirty_writeback_interval ext4: remove useless s_dirt assignment ext4: write superblock only once on unmount ext4: do not mark superblock as dirty unnecessarily ext4: correct ext4_punch_hole return codes ext4: remove restrictive checks for EOFBLOCKS_FL ext4: always set then trimmed blocks count into len ext4: fix trimmed block count accunting ext4: fix start and len arguments handling in ext4_trim_fs() ext4: update s_free_{inodes,blocks}_count during online resize ext4: change some printk() calls to use ext4_msg() instead ext4: avoid output message interleaving in ext4_error_<foo>() ext4: remove trailing newlines from ext4_msg() and ext4_error() messages ext4: add no_printk argument validation, fix fallout ext4: remove redundant "EXT4-fs: " from uses of ext4_msg ext4: give more helpful error message in ext4_ext_rm_leaf() ext4: remove unused code from ext4_ext_map_blocks() ext4: rewrite punch hole to use ext4_ext_remove_space() jbd2: cleanup journal tail after transaction commit ...
2012-03-24Fix potential endless loop in kswapd when compaction is not enabledRik van Riel
We should only test compaction_suitable if the kernel is built with CONFIG_COMPACTION, otherwise the stub compaction_suitable function will always return COMPACT_SKIPPED and send kswapd into an infinite loop. Reported-by: Anton Blanchard <anton@samba.org> Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-23coredump: add VM_NODUMP, MADV_NODUMP, MADV_CLEAR_NODUMPJason Baron
Since we no longer need the VM_ALWAYSDUMP flag, let's use the freed bit for 'VM_NODUMP' flag. The idea is is to add a new madvise() flag: MADV_DONTDUMP, which can be set by applications to specifically request memory regions which should not dump core. The specific application I have in mind is qemu: we can add a flag there that wouldn't dump all of guest memory when qemu dumps core. This flag might also be useful for security sensitive apps that want to absolutely make sure that parts of memory are not dumped. To clear the flag use: MADV_DODUMP. [akpm@linux-foundation.org: s/MADV_NODUMP/MADV_DONTDUMP/, s/MADV_CLEAR_NODUMP/MADV_DODUMP/, per Roland] [akpm@linux-foundation.org: fix up the architectures which broke] Signed-off-by: Jason Baron <jbaron@redhat.com> Acked-by: Roland McGrath <roland@hack.frob.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Avi Kivity <avi@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-23coredump: remove VM_ALWAYSDUMP flagJason Baron
The motivation for this patchset was that I was looking at a way for a qemu-kvm process, to exclude the guest memory from its core dump, which can be quite large. There are already a number of filter flags in /proc/<pid>/coredump_filter, however, these allow one to specify 'types' of kernel memory, not specific address ranges (which is needed in this case). Since there are no more vma flags available, the first patch eliminates the need for the 'VM_ALWAYSDUMP' flag. The flag is used internally by the kernel to mark vdso and vsyscall pages. However, it is simple enough to check if a vma covers a vdso or vsyscall page without the need for this flag. The second patch then replaces the 'VM_ALWAYSDUMP' flag with a new 'VM_NODUMP' flag, which can be set by userspace using new madvise flags: 'MADV_DONTDUMP', and unset via 'MADV_DODUMP'. The core dump filters continue to work the same as before unless 'MADV_DONTDUMP' is set on the region. The qemu code which implements this features is at: http://people.redhat.com/~jbaron/qemu-dump/qemu-dump.patch In my testing the qemu core dump shrunk from 383MB -> 13MB with this patch. I also believe that the 'MADV_DONTDUMP' flag might be useful for security sensitive apps, which might want to select which areas are dumped. This patch: The VM_ALWAYSDUMP flag is currently used by the coredump code to indicate that a vma is part of a vsyscall or vdso section. However, we can determine if a vma is in one these sections by checking it against the gate_vma and checking for a non-NULL return value from arch_vma_name(). Thus, freeing a valuable vma bit. Signed-off-by: Jason Baron <jbaron@redhat.com> Acked-by: Roland McGrath <roland@hack.frob.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Avi Kivity <avi@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-23signal: oom_kill_task: use SEND_SIG_FORCED instead of force_sig()Oleg Nesterov
Change oom_kill_task() to use do_send_sig_info(SEND_SIG_FORCED) instead of force_sig(SIGKILL). With the recent changes we do not need force_ to kill the CLONE_NEWPID tasks. And this is more correct. force_sig() can race with the exiting thread even if oom_kill_task() checks p->mm != NULL, while do_send_sig_info(group => true) kille the whole process. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Anton Vorontsov <anton.vorontsov@linaro.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-23mm: hugetlb: cleanup duplicated code in unmapping vm rangeHillf Danton
Fix code duplication in __unmap_hugepage_range(), such as pte_page() and huge_pte_none(). Signed-off-by: Hillf Danton <dhillf@gmail.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-23mm: fix testorder interaction between two kswapd patchesHugh Dickins
Adjusting cc715d99e529 "mm: vmscan: forcibly scan highmem if there are too many buffer_heads pinning highmem" for -stable reveals that it was slightly wrong once on top of fe2c2a106663 "vmscan: reclaim at order 0 when compaction is enabled", which specifically adds testorder for the zone_watermark_ok_safe() test. Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22Merge tag 'stable/for-linus-3.4' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm Pull cleancache changes from Konrad Rzeszutek Wilk: "This has some patches for the cleancache API that should have been submitted a _long_ time ago. They are basically cleanups: - rename of flush to invalidate - moving reporting of statistics into debugfs - use __read_mostly as necessary. Oh, and also the MAINTAINERS file change. The files (except the MAINTAINERS file) have been in #linux-next for months now. The late addition of MAINTAINERS file is a brain-fart on my side - didn't realize I needed that just until I was typing this up - and I based that patch on v3.3 - so the tree is on top of v3.3." * tag 'stable/for-linus-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm: MAINTAINERS: Adding cleancache API to the list. mm: cleancache: Use __read_mostly as appropiate. mm: cleancache: report statistics via debugfs instead of sysfs. mm: zcache/tmem/cleancache: s/flush/invalidate/ mm: cleancache: s/flush/invalidate/
2012-03-22Merge branch 'x86-mce-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull MCE changes from Ingo Molnar. * 'x86-mce-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mce: Fix return value of mce_chrdev_read() when erst is disabled x86/mce: Convert static array of pointers to per-cpu variables x86/mce: Replace hard coded hex constants with symbolic defines x86/mce: Recognise machine check bank signature for data path error x86/mce: Handle "action required" errors x86/mce: Add mechanism to safely save information in MCE handler x86/mce: Create helper function to save addr/misc when needed HWPOISON: Add code to handle "action required" errors. HWPOISON: Clean up memory_failure() vs. __memory_failure()
2012-03-22Merge branch 'akpm' (Andrew's patch-bomb)Linus Torvalds
Merge first batch of patches from Andrew Morton: "A few misc things and all the MM queue" * emailed from Andrew Morton <akpm@linux-foundation.org>: (92 commits) memcg: avoid THP split in task migration thp: add HPAGE_PMD_* definitions for !CONFIG_TRANSPARENT_HUGEPAGE memcg: clean up existing move charge code mm/memcontrol.c: remove unnecessary 'break' in mem_cgroup_read() mm/memcontrol.c: remove redundant BUG_ON() in mem_cgroup_usage_unregister_event() mm/memcontrol.c: s/stealed/stolen/ memcg: fix performance of mem_cgroup_begin_update_page_stat() memcg: remove PCG_FILE_MAPPED memcg: use new logic for page stat accounting memcg: remove PCG_MOVE_LOCK flag from page_cgroup memcg: simplify move_account() check memcg: remove EXPORT_SYMBOL(mem_cgroup_update_page_stat) memcg: kill dead prev_priority stubs memcg: remove PCG_CACHE page_cgroup flag memcg: let css_get_next() rely upon rcu_read_lock() cgroup: revert ss_id_lock to spinlock idr: make idr_get_next() good for rcu_read_lock() memcg: remove unnecessary thp check in page stat accounting memcg: remove redundant returns memcg: enum lru_list lru ...
2012-03-21mm: export dirty_writeback_intervalArtem Bityutskiy
Export 'dirty_writeback_interval' to make it visible to file-systems. We are going to push superblock management down to file-systems and get rid of the 'sync_supers' kernel thread completly. Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2012-03-21memcg: avoid THP split in task migrationNaoya Horiguchi
Currently we can't do task migration among memory cgroups without THP split, which means processes heavily using THP experience large overhead in task migration. This patch introduces the code for moving charge of THP and makes THP more valuable. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <dhillf@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21thp: add HPAGE_PMD_* definitions for !CONFIG_TRANSPARENT_HUGEPAGENaoya Horiguchi
These macros will be used in a later patch, where all usages are expected to be optimized away without #ifdef CONFIG_TRANSPARENT_HUGEPAGE. But to detect unexpected usages, we convert the existing BUG() to BUILD_BUG(). [akpm@linux-foundation.org: fix build in mm/pgtable-generic.c] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <dhillf@gmail.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: clean up existing move charge codeNaoya Horiguchi
- Replace lengthy function name is_target_pte_for_mc() with a shorter one in order to avoid ugly line breaks. - explicitly use MC_TARGET_* instead of simply using integers. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Hillf Danton <dhillf@gmail.com> Cc: David Rientjes <rientjes@google.com> Acked-by: Hillf Danton <dhillf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21mm/memcontrol.c: remove unnecessary 'break' in mem_cgroup_read()Jeff Liu
Signed-off-by: Jie Liu <jeff.liu@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21mm/memcontrol.c: remove redundant BUG_ON() in ↵Anton Vorontsov
mem_cgroup_usage_unregister_event() In the following code: if (type == _MEM) thresholds = &memcg->thresholds; else if (type == _MEMSWAP) thresholds = &memcg->memsw_thresholds; else BUG(); BUG_ON(!thresholds); The BUG_ON() seems redundant. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21mm/memcontrol.c: s/stealed/stolen/Andrew Morton
A grammatical fix. Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: fix performance of mem_cgroup_begin_update_page_stat()KAMEZAWA Hiroyuki
mem_cgroup_begin_update_page_stat() should be very fast because it's called very frequently. Now, it needs to look up page_cgroup and its memcg....this is slow. This patch adds a global variable to check "any memcg is moving or not". With this, the caller doesn't need to visit page_cgroup and memcg. Here is a test result. A test program makes page faults onto a file, MAP_SHARED and makes each page's page_mapcount(page) > 1, and free the range by madvise() and page fault again. This program causes 26214400 times of page fault onto a file(size was 1G.) and shows shows the cost of mem_cgroup_begin_update_page_stat(). Before this patch for mem_cgroup_begin_update_page_stat() [kamezawa@bluextal test]$ time ./mmap 1G real 0m21.765s user 0m5.999s sys 0m15.434s 27.46% mmap mmap [.] reader 21.15% mmap [kernel.kallsyms] [k] page_fault 9.17% mmap [kernel.kallsyms] [k] filemap_fault 2.96% mmap [kernel.kallsyms] [k] __do_fault 2.83% mmap [kernel.kallsyms] [k] __mem_cgroup_begin_update_page_stat After this patch [root@bluextal test]# time ./mmap 1G real 0m21.373s user 0m6.113s sys 0m15.016s In usual path, calls to __mem_cgroup_begin_update_page_stat() goes away. Note: we may be able to remove this optimization in future if we can get pointer to memcg directly from struct page. [akpm@linux-foundation.org: don't return a void] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Greg Thelen <gthelen@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: remove PCG_FILE_MAPPEDKAMEZAWA Hiroyuki
With the new lock scheme for updating memcg's page stat, we don't need a flag PCG_FILE_MAPPED which was duplicated information of page_mapped(). [hughd@google.com: cosmetic fix] [hughd@google.com: add comment to MEM_CGROUP_CHARGE_TYPE_MAPPED case in __mem_cgroup_uncharge_common()] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Greg Thelen <gthelen@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: use new logic for page stat accountingKAMEZAWA Hiroyuki
Now, page-stat-per-memcg is recorded into per page_cgroup flag by duplicating page's status into the flag. The reason is that memcg has a feature to move a page from a group to another group and we have race between "move" and "page stat accounting", Under current logic, assume CPU-A and CPU-B. CPU-A does "move" and CPU-B does "page stat accounting". When CPU-A goes 1st, CPU-A CPU-B update "struct page" info. move_lock_mem_cgroup(memcg) see pc->flags copy page stat to new group overwrite pc->mem_cgroup. move_unlock_mem_cgroup(memcg) move_lock_mem_cgroup(mem) set pc->flags update page stat accounting move_unlock_mem_cgroup(mem) stat accounting is guarded by move_lock_mem_cgroup() and "move" logic (CPU-A) doesn't see changes in "struct page" information. But it's costly to have the same information both in 'struct page' and 'struct page_cgroup'. And, there is a potential problem. For example, assume we have PG_dirty accounting in memcg. PG_..is a flag for struct page. PCG_ is a flag for struct page_cgroup. (This is just an example. The same problem can be found in any kind of page stat accounting.) CPU-A CPU-B TestSet PG_dirty (delay) TestClear PG_dirty if (TestClear(PCG_dirty)) memcg->nr_dirty-- if (TestSet(PCG_dirty)) memcg->nr_dirty++ Here, memcg->nr_dirty = +1, this is wrong. This race was reported by Greg Thelen <gthelen@google.com>. Now, only FILE_MAPPED is supported but fortunately, it's serialized by page table lock and this is not real bug, _now_, If this potential problem is caused by having duplicated information in struct page and struct page_cgroup, we may be able to fix this by using original 'struct page' information. But we'll have a problem in "move account" Assume we use only PG_dirty. CPU-A CPU-B TestSet PG_dirty (delay) move_lock_mem_cgroup() if (PageDirty(page)) new_memcg->nr_dirty++ pc->mem_cgroup = new_memcg; move_unlock_mem_cgroup() move_lock_mem_cgroup() memcg = pc->mem_cgroup new_memcg->nr_dirty++ accounting information may be double-counted. This was original reason to have PCG_xxx flags but it seems PCG_xxx has another problem. I think we need a bigger lock as move_lock_mem_cgroup(page) TestSetPageDirty(page) update page stats (without any checks) move_unlock_mem_cgroup(page) This fixes both of problems and we don't have to duplicate page flag into page_cgroup. Please note: move_lock_mem_cgroup() is held only when there are possibility of "account move" under the system. So, in most path, status update will go without atomic locks. This patch introduces mem_cgroup_begin_update_page_stat() and mem_cgroup_end_update_page_stat() both should be called at modifying 'struct page' information if memcg takes care of it. as mem_cgroup_begin_update_page_stat() modify page information mem_cgroup_update_page_stat() => never check any 'struct page' info, just update counters. mem_cgroup_end_update_page_stat(). This patch is slow because we need to call begin_update_page_stat()/ end_update_page_stat() regardless of accounted will be changed or not. A following patch adds an easy optimization and reduces the cost. [akpm@linux-foundation.org: s/lock/locked/] [hughd@google.com: fix deadlock by avoiding stat lock when anon] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Greg Thelen <gthelen@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: remove PCG_MOVE_LOCK flag from page_cgroupKAMEZAWA Hiroyuki
PCG_MOVE_LOCK is used for bit spinlock to avoid race between overwriting pc->mem_cgroup and page statistics accounting per memcg. This lock helps to avoid the race but the race is very rare because moving tasks between cgroup is not a usual job. So, it seems using 1bit per page is too costly. This patch changes this lock as per-memcg spinlock and removes PCG_MOVE_LOCK. If smaller lock is required, we'll be able to add some hashes but I'd like to start from this. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: simplify move_account() checkKAMEZAWA Hiroyuki
In memcg, for avoiding take-lock-irq-off at accessing page_cgroup, a logic, flag + rcu_read_lock(), is used. This works as following CPU-A CPU-B rcu_read_lock() set flag if(flag is set) take heavy lock do job. synchronize_rcu() rcu_read_unlock() take heavy lock. In recent discussion, it's argued that using per-cpu value for this flag just complicates the code because 'set flag' is very rare. This patch changes 'flag' implementation from percpu to atomic_t. This will be much simpler. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ying Han <yinghan@google.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: remove EXPORT_SYMBOL(mem_cgroup_update_page_stat)KAMEZAWA Hiroyuki
As described in the log, I guess EXPORT was for preparing dirty accounting. But _now_, we don't need to export this. Remove this for now. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ying Han <yinghan@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: remove PCG_CACHE page_cgroup flagKAMEZAWA Hiroyuki
We record 'the page is cache' with the PCG_CACHE bit in page_cgroup. Here, "CACHE" means anonymous user pages (and SwapCache). This doesn't include shmem. Considering callers, at charge/uncharge, the caller should know what the page is and we don't need to record it by using one bit per page. This patch removes PCG_CACHE bit and make callers of mem_cgroup_charge_statistics() to specify what the page is. About page migration: Mapping of the used page is not touched during migra tion (see page_remove_rmap) so we can rely on it and push the correct charge type down to __mem_cgroup_uncharge_common from end_migration for unused page. The force flag was misleading was abused for skipping the needless page_mapped() / PageCgroupMigration() check, as we know the unused page is no longer mapped and cleared the migration flag just a few lines up. But doing the checks is no biggie and it's not worth adding another flag just to skip them. [akpm@linux-foundation.org: checkpatch fixes] [hughd@google.com: fix PageAnon uncharging] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Ying Han <yinghan@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: remove unnecessary thp check in page stat accountingKAMEZAWA Hiroyuki
Commit e94c8a9cbce1 ("memcg: make mem_cgroup_split_huge_fixup() more efficient") removed move_lock_page_cgroup(). So we do not have to check PageTransHuge in mem_cgroup_update_page_stat() and fallback into the locked accounting because both move_account() and thp split are done with compound_lock so they cannot race. The race between update vs. move is protected by mem_cgroup_stealed. PageTransHuge pages shouldn't appear in this code path currently because we are tracking only file pages at the moment but later we are planning to track also other pages (e.g. mlocked ones). Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Acked-by: Michal Hocko <mhocko@suse.cz> Cc: David Rientjes <rientjes@google.com> Acked-by: Ying Han<yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: remove redundant returnsHugh Dickins
Remove redundant returns from ends of functions, and one blank line. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Kirill A. Shutemov <kirill@shutemov.name> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: enum lru_list lruHugh Dickins
Mostly we use "enum lru_list lru": change those few "l"s to "lru"s. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Kirill A. Shutemov <kirill@shutemov.name> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: lru_size instead of MEM_CGROUP_ZSTATHugh Dickins
I never understood why we need a MEM_CGROUP_ZSTAT(mz, idx) macro to obscure the LRU counts. For easier searching? So call it lru_size rather than bare count (lru_length sounds better, but would be wrong, since each huge page raises lru_size hugely). Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill@shutemov.name> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21memcg: replace mem and mem_cont stragglersHugh Dickins
Replace mem and mem_cont stragglers in memcontrol.c by memcg. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Kirill A. Shutemov <kirill@shutemov.name> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21swap: don't do discard if no discard option addedShaohua Li
When swapon() was not passed the SWAP_FLAG_DISCARD option, sys_swapon() will still perform a discard operation. This can cause problems if discard is slow or buggy. Reverse the order of the check so that a discard operation is performed only if the sys_swapon() caller is attempting to enable discard. Signed-off-by: Shaohua Li <shli@fusionio.com> Reported-by: Holger Kiehl <Holger.Kiehl@dwd.de> Tested-by: Holger Kiehl <Holger.Kiehl@dwd.de> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21mm: forbid lumpy-reclaim in shrink_active_list()Konstantin Khlebnikov
Reset the reclaim mode in shrink_active_list() to RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC. (sync/async sign is used only in shrink_page_list and does not affect shrink_active_list) Currenly shrink_active_list() sometimes works in lumpy-reclaim mode, if RECLAIM_MODE_LUMPYRECLAIM is left over from an earlier shrink_inactive_list(). Meanwhile, in age_active_anon() sc->reclaim_mode is totally zero. So the current behavior is too complex and confusing, and this looks like bug. In general, shrink_active_list() populates the inactive list for the next shrink_inactive_list(). Lumpy shring_inactive_list() isolates pages around the chosen one from both the active and inactive lists. So, there is no reason for lumpy isolation in shrink_active_list(). See also: https://lkml.org/lkml/2012/3/15/583 Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Proposed-by: Hugh Dickins <hughd@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21mmap.c: fix comment for __insert_vm_struct()Kautuk Consul
The comment above __insert_vm_struct seems to suggest that this function is also going to link the VMA with the anon_vma, but this is not true. This function only links the VMA to the mm->mm_rb tree and the mm->mmap linked list. [akpm@linux-foundation.org: improve comment layout and text] Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21page_alloc: remove unused find_zone_movable_pfns_for_nodes() argumentKautuk Consul
find_zone_movable_pfns_for_nodes() does not use its argument. Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21page_alloc.c: remove add_from_early_node_map()Kautuk Consul
add_from_early_node_map() is unused. Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21hugetlbfs: fix alignment of huge page requestsSteven Truelove
When calling shmget() with SHM_HUGETLB, shmget aligns the request size to PAGE_SIZE, but this is not sufficient. Modify hugetlb_file_setup() to align requests to the huge page size, and to accept an address argument so that all alignment checks can be performed in hugetlb_file_setup(), rather than in its callers. Change newseg() and mmap_pgoff() to match the new prototype and eliminate a now redundant alignment check. [akpm@linux-foundation.org: fix build] Signed-off-by: Steven Truelove <steven.truelove@utoronto.ca> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21mm, counters: fold __sync_task_rss_stat() into sync_mm_rss()David Rientjes
There's no difference between sync_mm_rss() and __sync_task_rss_stat(), so fold the latter into the former. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21mm, counters: remove task argument to sync_mm_rss() and __sync_task_rss_stat()David Rientjes
sync_mm_rss() can only be used for current to avoid race conditions in iterating and clearing its per-task counters. Remove the task argument for it and its helper function, __sync_task_rss_stat(), to avoid thinking it can be used safely for anything other than current. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21hugepages: fix use after free bug in "quota" handlingDavid Gibson
hugetlbfs_{get,put}_quota() are badly named. They don't interact with the general quota handling code, and they don't much resemble its behaviour. Rather than being about maintaining limits on on-disk block usage by particular users, they are instead about maintaining limits on in-memory page usage (including anonymous MAP_PRIVATE copied-on-write pages) associated with a particular hugetlbfs filesystem instance. Worse, they work by having callbacks to the hugetlbfs filesystem code from the low-level page handling code, in particular from free_huge_page(). This is a layering violation of itself, but more importantly, if the kernel does a get_user_pages() on hugepages (which can happen from KVM amongst others), then the free_huge_page() can be delayed until after the associated inode has already been freed. If an unmount occurs at the wrong time, even the hugetlbfs superblock where the "quota" limits are stored may have been freed. Andrew Barry proposed a patch to fix this by having hugepages, instead of storing a pointer to their address_space and reaching the superblock from there, had the hugepages store pointers directly to the superblock, bumping the reference count as appropriate to avoid it being freed. Andrew Morton rejected that version, however, on the grounds that it made the existing layering violation worse. This is a reworked version of Andrew's patch, which removes the extra, and some of the existing, layering violation. It works by introducing the concept of a hugepage "subpool" at the lower hugepage mm layer - that is a finite logical pool of hugepages to allocate from. hugetlbfs now creates a subpool for each filesystem instance with a page limit set, and a pointer to the subpool gets added to each allocated hugepage, instead of the address_space pointer used now. The subpool has its own lifetime and is only freed once all pages in it _and_ all other references to it (i.e. superblocks) are gone. subpools are optional - a NULL subpool pointer is taken by the code to mean that no subpool limits are in effect. Previous discussion of this bug found in: "Fix refcounting in hugetlbfs quota handling.". See: https://lkml.org/lkml/2011/8/11/28 or http://marc.info/?l=linux-mm&m=126928970510627&w=1 v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to alloc_huge_page() - since it already takes the vma, it is not necessary. Signed-off-by: Andrew Barry <abarry@cray.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21ksm: cleanup: introduce find_mergeable_vma()Bob Liu
There are multiple places which perform the same check. Add a new find_mergeable_vma() to handle this. Signed-off-by: Bob Liu <lliubbo@gmail.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21cpuset: mm: reduce large amounts of memory barrier related damage v3Mel Gorman
Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when changing cpuset's mems") wins a super prize for the largest number of memory barriers entered into fast paths for one commit. [get|put]_mems_allowed is incredibly heavy with pairs of full memory barriers inserted into a number of hot paths. This was detected while investigating at large page allocator slowdown introduced some time after 2.6.32. The largest portion of this overhead was shown by oprofile to be at an mfence introduced by this commit into the page allocator hot path. For extra style points, the commit introduced the use of yield() in an implementation of what looks like a spinning mutex. This patch replaces the full memory barriers on both read and write sides with a sequence counter with just read barriers on the fast path side. This is much cheaper on some architectures, including x86. The main bulk of the patch is the retry logic if the nodemask changes in a manner that can cause a false failure. While updating the nodemask, a check is made to see if a false failure is a risk. If it is, the sequence number gets bumped and parallel allocators will briefly stall while the nodemask update takes place. In a page fault test microbenchmark, oprofile samples from __alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The actual results were 3.3.0-rc3 3.3.0-rc3 rc3-vanilla nobarrier-v2r1 Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%) Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%) Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%) Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%) Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%) Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%) Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%) Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%) Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%) Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%) Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%) Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%) Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%) Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%) Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%) MMTests Statistics: duration Sys Time Running Test (seconds) 135.68 132.17 User+Sys Time Running Test (seconds) 164.2 160.13 Total Elapsed Time (seconds) 123.46 120.87 The overall improvement is small but the System CPU time is much improved and roughly in correlation to what oprofile reported (these performance figures are without profiling so skew is expected). The actual number of page faults is noticeably improved. For benchmarks like kernel builds, the overall benefit is marginal but the system CPU time is slightly reduced. To test the actual bug the commit fixed I opened two terminals. The first ran within a cpuset and continually ran a small program that faulted 100M of anonymous data. In a second window, the nodemask of the cpuset was continually randomised in a loop. Without the commit, the program would fail every so often (usually within 10 seconds) and obviously with the commit everything worked fine. With this patch applied, it also worked fine so the fix should be functionally equivalent. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Miao Xie <miaox@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21mm, memcg: pass charge order to oom killerDavid Rientjes
The oom killer typically displays the allocation order at the time of oom as a part of its diangostic messages (for global, cpuset, and mempolicy ooms). The memory controller may also pass the charge order to the oom killer so it can emit the same information. This is useful in determining how large the memory allocation is that triggered the oom killer. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>