- 11 Jan, 2012 40 commits
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Joe Perches authored
commit 38576af1 ("mmc: sdhci: make sdhci-of device drivers self registered") moved the files around. Update the patterns. Signed-off-by:
Joe Perches <joe@perches.com> Cc: Shawn Guo <shawn.guo@linaro.org> Cc: Chris Ball <cjb@laptop.org> Acked-by:
Anton Vorontsov <cbouatmailru@gmail.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Joe Perches authored
commit 8959e743 ("mfd: Delete ab3550 driver") removed the driver, update the patterns. Signed-off-by:
Linus Walleij <linus.walleij@linaro.org> Signed-off-by:
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Joe Perches authored
Commit f8fc7298 ("[media] marvell-cam: Move cafe-ccic into its own directory") moved the files, update the pattern. Signed-off-by:
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Joe Perches authored
Commit c103de24 ("gpio: reorganize drivers") renamed the file, update the pattern. Signed-off-by:
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Joe Perches authored
Commit c103de24 ("gpio: reorganize drivers") renamed the files, update the patterns. Signed-off-by:
Grant Likely <grant.likely@secretlab.ca> Acked-by:
Michael Hennerich <michael.hennerich@analog.com> Signed-off-by:
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Joe Perches authored
Track renames and missing or deleted files. Signed-off-by:
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Ian Campbell authored
I happen to have had a commit to various network drivers since the big renaming/reorg which happened to drivers/net recently. This means that I now appear to be in the top few commit signers (by %age) for many of them so am getting sent all sorts of stuff and people who are involved with the driver are not. e.g. (to pick one at random): $ ./scripts/get_maintainer.pl -f drivers/net/ethernet/nvidia/forcedeth.c "David S. Miller" <davem@davemloft.net> (commit_signer:5/7=71%) Ian Campbell <ian.campbell@citrix.com> (commit_signer:2/7=29%) Eric Dumazet <eric.dumazet@gmail.com> (commit_signer:1/7=14%) Jeff Kirsher <jeffrey.t.kirsher@intel.com> (commit_signer:1/7=14%) Jiri Pirko <jpirko@redhat.com> (commit_signer:1/7=14%) netdev@vger.kernel.org (open list:NETWORKING DRIVERS) linux-kernel@vger.kernel.org (open list) With the following patch the renames are followed and the result appears much more sensible: $ ./scripts/get_maintainer.pl -f drivers/net/ethernet/nvidia/forcedeth.c "David S. Miller" <davem@davemloft.net> (commit_signer:31/34=91%) Joe Perches <joe@perches.com> (commit_signer:11/34=32%) Szymon Janc <szymon@janc.net.pl> (commit_signer:5/34=15%) Jiri Pirko <jpirko@redhat.com> (commit_signer:3/34=9%) Paul <paul.gortmaker@windriver.com> (commit_signer:2/34=6%) netdev@vger.kernel.org (open list:NETWORKING DRIVERS) linux-kernel@vger.kernel.org (open list) Signed-off-by:Ian Campbell <Ian.Campbell@citrix.com> Acked-by:
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Minchan Kim authored
vmap_area->private is void* but we don't use the field for various purpose but use only for vm_struct. So change it to a vm_struct* with naming to improve for readability and type checking. Signed-off-by:
Minchan Kim <minchan@kernel.org> Acked-by:
David Rientjes <rientjes@google.com> Signed-off-by:
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Hillf Danton authored
It is not the tag page but the cursor page that we should process, and it looks a typo. Signed-off-by:
Hillf Danton <dhillf@gmail.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Acked-by:
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by:
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Hugh Dickins authored
Lumpy reclaim does well to stop at a PageAnon when there's no swap, but better is to stop at any PageSwapBacked, which includes shmem/tmpfs too. Signed-off-by:
Hugh Dickins <hughd@google.com> Reviewed-by:
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Wang Sheng-Hui authored
lru_to_page is not used in mm/migrate.c. Signed-off-by:
Wang Sheng-Hui <shhuiw@gmail.com> Acked-by:
Mel Gorman <mgorman@suse.de> Acked-by:
Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by:
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Hillf Danton authored
If we have to hand back the newly allocated huge page to page allocator, for any reason, the changed counter should be recovered. This affects only s390 at present. Signed-off-by:
Michal Hocko <mhocko@suse.cz> Acked-by:
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by:
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Tejun Heo authored
mempool modifies gfp_mask so that the backing allocator doesn't try too hard or trigger warning message when there's pool to fall back on. In addition, for the first try, it removes __GFP_WAIT and IO, so that it doesn't trigger reclaim or wait when allocation can be fulfilled from pool; however, when that allocation fails and pool is empty too, it waits for the pool to be replenished before retrying. Allocation which could have succeeded after a bit of reclaim has to wait on the reserved items and it's not like mempool doesn't retry with __GFP_WAIT and IO. It just does that *after* someone returns an element, pointlessly delaying things. Fix it by retrying immediately if the first round of allocation attempts w/o __GFP_WAIT and IO fails. [akpm@linux-foundation.org: shorten the lock hold time] Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
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Tejun Heo authored
mempool_destroy() is a thin wrapper around free_pool(). The only thing it adds is BUG_ON(pool->curr_nr != pool->min_nr). The intention seems to be to enforce that all allocated elements are freed; however, the BUG_ON() can't achieve that (it doesn't know anything about objects above min_nr) and incorrect as mempool_resize() is allowed to leave the pool extended but not filled. Furthermore, panicking is way worse than any memory leak and there are better debug tools to track memory leaks. Drop the BUG_ON() from mempool_destory() and as that leaves the function identical to free_pool(), replace it. Signed-off-by:
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Tejun Heo authored
mempool_alloc/free() use undocumented smp_mb()'s. The code is slightly broken and misleading. The lockless part is in mempool_free(). It wants to determine whether the item being freed needs to be returned to the pool or backing allocator without grabbing pool->lock. Two things need to be guaranteed for correct operation. 1. pool->curr_nr + #allocated should never dip below pool->min_nr. 2. Waiters shouldn't be left dangling. For #1, The only necessary condition is that curr_nr visible at free is from after the allocation of the element being freed (details in the comment). For most cases, this is true without any barrier but there can be fringe cases where the allocated pointer is passed to the freeing task without going through memory barriers. To cover this case, wmb is necessary before returning from allocation and rmb is necessary before reading curr_nr. IOW, ALLOCATING TASK FREEING TASK update pool state after alloc; wmb(); pass pointer to freeing task; read pointer; rmb(); read pool state to free; The current code doesn't have wmb after pool update during allocation and may theoretically, on machines where unlock doesn't behave as full wmb, lead to pool depletion and deadlock. smp_wmb() needs to be added after successful allocation from reserved elements and smp_mb() in mempool_free() can be replaced with smp_rmb(). For #2, the waiter needs to add itself to waitqueue and then check the wait condition and the waker needs to update the wait condition and then wake up. Because waitqueue operations always go through full spinlock synchronization, there is no need for extra memory barriers. Furthermore, mempool_alloc() is already holding pool->lock when it decides that it needs to wait. There is no reason to do unlock - add waitqueue - test condition again. It can simply add itself to waitqueue while holding pool->lock and then unlock and sleep. This patch adds smp_wmb() after successful allocation from reserved pool, replaces smp_mb() in mempool_free() with smp_rmb() and extend pool->lock over waitqueue addition. More importantly, it explains what memory barriers do and how the lockless testing is correct. -v2: Oleg pointed out that unlock doesn't imply wmb. Added explicit smp_wmb() after successful allocation from reserved pool and updated comments accordingly. Signed-off-by: -
Wang Sheng-Hui authored
migration_entry_wait() can also be called from hugetlb_fault() now. Remove the incorrect comment. Signed-off-by:
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KOSAKI Motohiro authored
mpol_equal() logically returns a boolean. Use a bool type to slightly improve readability. Signed-off-by:
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Hillf Danton authored
The computation for pgoff is incorrect, at least with (vma->vm_pgoff >> PAGE_SHIFT) involved. It is fixed with the available method if HPAGE_SIZE is concerned in page cache lookup. [akpm@linux-foundation.org: use vma_hugecache_offset() directly, per Michal] Signed-off-by:
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Minchan Kim authored
It's pointless to continue reclaiming when we have no swap space and lots of anon pages in the inactive list. Without this patch, it is possible when swap is disabled to continue trying to reclaim when there are only anonymous pages in the system even though that will not make any progress. Signed-off-by:
Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by:
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Johannes Weiner authored
The loop that frees pages to the page allocator while bootstrapping tries to free higher-order blocks only when the starting address is aligned to that block size. Otherwise it will free all pages on that node one-by-one. Change it to free individual pages up to the first aligned block and then try higher-order frees from there. Signed-off-by:
Johannes Weiner <hannes@cmpxchg.org> Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Cc: Tejun Heo <tj@kernel.org> Signed-off-by:
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Johannes Weiner authored
The area node_bootmem_map represents is aligned to BITS_PER_LONG, and all bits in any aligned word of that map valid. When the represented area extends beyond the end of the node, the non-existant pages will be marked as reserved. As a result, when freeing a page block, doing an explicit range check for whether that block is within the node's range is redundant as the bitmap is consulted anyway to see whether all pages in the block are unreserved. Signed-off-by:
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Johannes Weiner authored
__free_pages_bootmem() used to special-case higher-order frees to save individual page checking with free_pages_bulk(). Nowadays, both zero order and non-zero order frees use free_pages(), which checks each individual page anyway, and so there is little point in making the distinction anymore. The higher-order loop will work just fine for zero order pages. Signed-off-by:
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KAMEZAWA Hiroyuki authored
oom_score_adj is used for guarding processes from OOM-Killer. One of problem is that it's inherited at fork(). When a daemon set oom_score_adj and make children, it's hard to know where the value is set. This patch adds some tracepoints useful for debugging. This patch adds 3 trace points. - creating new task - renaming a task (exec) - set oom_score_adj To debug, users need to enable some trace pointer. Maybe filtering is useful as # EVENT=/sys/kernel/debug/tracing/events/task/ # echo "oom_score_adj != 0" > $EVENT/task_newtask/filter # echo "oom_score_adj != 0" > $EVENT/task_rename/filter # echo 1 > $EVENT/enable # EVENT=/sys/kernel/debug/tracing/events/oom/ # echo 1 > $EVENT/enable output will be like this. # grep oom /sys/kernel/debug/tracing/trace bash-7699 [007] d..3 5140.744510: oom_score_adj_update: pid=7699 comm=bash oom_score_adj=-1000 bash-7699 [007] ...1 5151.818022: task_newtask: pid=7729 comm=bash clone_flags=1200011 oom_score_adj=-1000 ls-7729 [003] ...2 5151.818504: task_rename: pid=7729 oldcomm=bash newcomm=ls oom_score_adj=-1000 bash-7699 [002] ...1 5175.701468: task_newtask: pid=7730 comm=bash clone_flags=1200011 oom_score_adj=-1000 grep-7730 [007] ...2 5175.701993: task_rename: pid=7730 oldcomm=bash newcomm=grep oom_score_adj=-1000 Signed-off-by:
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KOSAKI Motohiro authored
commit 297c5eee ("mm: make the vma list be doubly linked") added the vm_prev member to vm_area_struct. We can simplify find_vma_prev() by using it. Also, this change helps to improve page fault performance because it has stronger locality of reference. Signed-off-by:
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Andrea Arcangeli authored
migrate was doing an rmap_walk with speculative lock-less access on pagetables. That could lead it to not serializing properly against mremap PT locks. But a second problem remains in the order of vmas in the same_anon_vma list used by the rmap_walk. If vma_merge succeeds in copy_vma, the src vma could be placed after the dst vma in the same_anon_vma list. That could still lead to migrate missing some pte. This patch adds an anon_vma_moveto_tail() function to force the dst vma at the end of the list before mremap starts to solve the problem. If the mremap is very large and there are a lots of parents or childs sharing the anon_vma root lock, this should still scale better than taking the anon_vma root lock around every pte copy practically for the whole duration of mremap. Update: Hugh noticed special care is needed in the error path where move_page_tables goes in the reverse direction, a second anon_vma_moveto_tail() call is needed in the error path. This program exercises the anon_vma_moveto_tail: === int main() { static struct timeval oldstamp, newstamp; long diffsec; char *p, *p2, *p3, *p4; if (posix_memalign((void **)&p, 2*1024*1024, SIZE)) perror("memalign"), exit(1); if (posix_memalign((void **)&p2, 2*1024*1024, SIZE)) perror("memalign"), exit(1); if (posix_memalign((void **)&p3, 2*1024*1024, SIZE)) perror("memalign"), exit(1); memset(p, 0xff, SIZE); printf("%p\n", p); memset(p2, 0xff, SIZE); memset(p3, 0x77, 4096); if (memcmp(p, p2, SIZE)) printf("error\n"); p4 = mremap(p+SIZE/2, SIZE/2, SIZE/2, MREMAP_FIXED|MREMAP_MAYMOVE, p3); if (p4 != p3) perror("mremap"), exit(1); p4 = mremap(p4, SIZE/2, SIZE/2, MREMAP_FIXED|MREMAP_MAYMOVE, p+SIZE/2); if (p4 != p+SIZE/2) perror("mremap"), exit(1); if (memcmp(p, p2, SIZE)) printf("error\n"); printf("ok\n"); return 0; } === $ perf probe -a anon_vma_moveto_tail Add new event: probe:anon_vma_moveto_tail (on anon_vma_moveto_tail) You can now use it on all perf tools, such as: perf record -e probe:anon_vma_moveto_tail -aR sleep 1 $ perf record -e probe:anon_vma_moveto_tail -aR ./anon_vma_moveto_tail 0x7f2ca2800000 ok [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.043 MB perf.data (~1860 samples) ] $ perf report --stdio 100.00% anon_vma_moveto [kernel.kallsyms] [k] anon_vma_moveto_tail Signed-off-by:Andrea Arcangeli <aarcange@redhat.com> Reported-by:
Nai Xia <nai.xia@gmail.com> Acked-by:
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Michal Hocko authored
Commit 88f5acf8 ("mm: page allocator: adjust the per-cpu counter threshold when memory is low") changed the form how free_pages is calculated but it forgot that we used to do free_pages - ((1 << order) - 1) so we ended up with off-by-two when calculating free_pages. Reported-by:
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Uwe Kleine-König authored
The first entry of bdata->node_bootmem_map holds the data for bdata->node_min_pfn up to bdata->node_min_pfn + BITS_PER_LONG - 1. So the test for freeing all pages of a single map entry can be slightly relaxed. Moreover use DIV_ROUND_UP in another place instead of open coding it. Signed-off-by:
Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Cc: Johannes Weiner <hannes@saeurebad.de> Signed-off-by:
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Hillf Danton authored
After isolated the current pfn will no longer be scanned and isolated if the next round is necessary, so push the isolate_migratepages search base of the given compact_control one step ahead. Signed-off-by:
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Johannes Weiner authored
Tell the page allocator that pages allocated for a buffered write are expected to become dirty soon. Signed-off-by:
Johannes Weiner <jweiner@redhat.com> Reviewed-by:
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Johannes Weiner authored
Tell the page allocator that pages allocated through grab_cache_page_write_begin() are expected to become dirty soon. Signed-off-by:
Minchan Kim <minchan.kim@gmail.com> Reviewed-by:
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Johannes Weiner authored
The maximum number of dirty pages that exist in the system at any time is determined by a number of pages considered dirtyable and a user-configured percentage of those, or an absolute number in bytes. This number of dirtyable pages is the sum of memory provided by all the zones in the system minus their lowmem reserves and high watermarks, so that the system can retain a healthy number of free pages without having to reclaim dirty pages. But there is a flaw in that we have a zoned page allocator which does not care about the global state but rather the state of individual memory zones. And right now there is nothing that prevents one zone from filling up with dirty pages while other zones are spared, which frequently leads to situations where kswapd, in order to restore the watermark of free pages, does indeed have to write pages from that zone's LRU list. This can interfere so badly with IO from the flusher threads that major filesystems (btrfs, xfs, ext4) mostly ignore write requests from reclaim already, taking away the VM's only possibility to keep such a zone balanced, aside from hoping the flushers will soon clean pages from that zone. Enter per-zone dirty limits. They are to a zone's dirtyable memory what the global limit is to the global amount of dirtyable memory, and try to make sure that no single zone receives more than its fair share of the globally allowed dirty pages in the first place. As the number of pages considered dirtyable excludes the zones' lowmem reserves and high watermarks, the maximum number of dirty pages in a zone is such that the zone can always be balanced without requiring page cleaning. As this is a placement decision in the page allocator and pages are dirtied only after the allocation, this patch allows allocators to pass __GFP_WRITE when they know in advance that the page will be written to and become dirty soon. The page allocator will then attempt to allocate from the first zone of the zonelist - which on NUMA is determined by the task's NUMA memory policy - that has not exceeded its dirty limit. At first glance, it would appear that the diversion to lower zones can increase pressure on them, but this is not the case. With a full high zone, allocations will be diverted to lower zones eventually, so it is more of a shift in timing of the lower zone allocations. Workloads that previously could fit their dirty pages completely in the higher zone may be forced to allocate from lower zones, but the amount of pages that "spill over" are limited themselves by the lower zones' dirty constraints, and thus unlikely to become a problem. For now, the problem of unfair dirty page distribution remains for NUMA configurations where the zones allowed for allocation are in sum not big enough to trigger the global dirty limits, wake up the flusher threads and remedy the situation. Because of this, an allocation that could not succeed on any of the considered zones is allowed to ignore the dirty limits before going into direct reclaim or even failing the allocation, until a future patch changes the global dirty throttling and flusher thread activation so that they take individual zone states into account. Test results 15M DMA + 3246M DMA32 + 504 Normal = 3765M memory 40% dirty ratio 16G USB thumb drive 10 runs of dd if=/dev/zero of=disk/zeroes bs=32k count=$((10 << 15)) seconds nr_vmscan_write (stddev) min| median| max xfs vanilla: 549.747( 3.492) 0.000| 0.000| 0.000 patched: 550.996( 3.802) 0.000| 0.000| 0.000 fuse-ntfs vanilla: 1183.094(53.178) 54349.000| 59341.000| 65163.000 patched: 558.049(17.914) 0.000| 0.000| 43.000 btrfs vanilla: 573.679(14.015) 156657.000| 460178.000| 606926.000 patched: 563.365(11.368) 0.000| 0.000| 1362.000 ext4 vanilla: 561.197(15.782) 0.000|2725438.000|4143837.000 patched: 568.806(17.496) 0.000| 0.000| 0.000 Signed-off-by:
Wu Fengguang <fengguang.wu@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Jan Kara <jack@suse.cz> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Chris Mason <chris.mason@oracle.com> Signed-off-by:
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Johannes Weiner authored
The next patch will introduce per-zone dirty limiting functions in addition to the traditional global dirty limiting. Rename determine_dirtyable_memory() to global_dirtyable_memory() before adding the zone-specific version, and fix up its documentation. Also, move the functions to determine the dirtyable memory and the function to calculate the dirty limit based on that together so that their relationship is more apparent and that they can be commented on as a group. Signed-off-by:
Mel Gorman <mel@suse.de> Reviewed-by:
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Johannes Weiner authored
Per-zone dirty limits try to distribute page cache pages allocated for writing across zones in proportion to the individual zone sizes, to reduce the likelihood of reclaim having to write back individual pages from the LRU lists in order to make progress. This patch: The amount of dirtyable pages should not include the full number of free pages: there is a number of reserved pages that the page allocator and kswapd always try to keep free. The closer (reclaimable pages - dirty pages) is to the number of reserved pages, the more likely it becomes for reclaim to run into dirty pages: +----------+ --- | anon | | +----------+ | | | | | | -- dirty limit new -- flusher new | file | | | | | | | | | -- dirty limit old -- flusher old | | | +----------+ --- reclaim | reserved | +----------+ | kernel | +----------+ This patch introduces a per-zone dirty reserve that takes both the lowmem reserve as well as the high watermark of the zone into account, and a global sum of those per-zone values that is subtracted from the global amount of dirtyable pages. The lowmem reserve is unavailable to page cache allocations and kswapd tries to keep the high watermark free. We don't want to end up in a situation where reclaim has to clean pages in order to balance zones. Not treating reserved pages as dirtyable on a global level is only a conceptual fix. In reality, dirty pages are not distributed equally across zones and reclaim runs into dirty pages on a regular basis. But it is important to get this right before tackling the problem on a per-zone level, where the distance between reclaim and the dirty pages is mostly much smaller in absolute numbers. [akpm@linux-foundation.org: fix highmem build] Signed-off-by: -
KOSAKI Motohiro authored
If we need to know a usecase, caller program name is critical important. Show it. Signed-off-by:
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David Rientjes authored
Calling alloc_pages_exact_node() means the allocation only passes the zonelist of a single node into the page allocator. If that node isn't online, it's zonelist may never have been initialized causing a strange oops that may not immediately be clear. I recently debugged an issue where node 0 wasn't online and an allocator was passing 0 to alloc_pages_exact_node() and it resulted in a NULL pointer on zonelist->_zoneref. If CONFIG_DEBUG_VM is enabled, though, it would be nice to catch this a bit earlier. Signed-off-by:
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Shawn Bohrer authored
Previously POSIX_FADV_DONTNEED would start writeback for the entire file when the bdi was not write congested. This negatively impacts performance if the file contains dirty pages outside of the requested range. This change uses __filemap_fdatawrite_range() to only initiate writeback for the requested range. Signed-off-by:
Shawn Bohrer <sbohrer@rgmadvisors.com> Acked-by:
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Stanislaw Gruszka authored
Disable slub debug facilities and allocate slabs at minimal order when debug_guardpage_minorder > 0 to increase probability to catch random memory corruption by cpu exception. Signed-off-by:
Stanislaw Gruszka <sgruszka@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by:
Christoph Lameter <cl@linux.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by:
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Stanislaw Gruszka authored
When debugging with CONFIG_DEBUG_PAGEALLOC and debug_guardpage_minorder > 0, we have lot of free pages that are not marked so. Snapshot code account them as savable, what cause hibernate memory preallocation failure. It is pretty hard to make hibernate allocation succeed with debug_guardpage_minorder=1. This change at least make it possible when system has relatively big amount of RAM. Signed-off-by:
Rafael J. Wysocki <rjw@sisk.pl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by:
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Stanislaw Gruszka authored
With CONFIG_DEBUG_PAGEALLOC configured, the CPU will generate an exception on access (read,write) to an unallocated page, which permits us to catch code which corrupts memory. However the kernel is trying to maximise memory usage, hence there are usually few free pages in the system and buggy code usually corrupts some crucial data. This patch changes the buddy allocator to keep more free/protected pages and to interlace free/protected and allocated pages to increase the probability of catching corruption. When the kernel is compiled with CONFIG_DEBUG_PAGEALLOC, debug_guardpage_minorder defines the minimum order used by the page allocator to grant a request. The requested size will be returned with the remaining pages used as guard pages. The default value of debug_guardpage_minorder is zero: no change from current behaviour. [akpm@linux-foundation.org: tweak documentation, s/flg/flag/] Signed-off-by:
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David Daney authored
We can place this in definitions that we expect the compiler to remove by dead code elimination. If this assertion fails, we get a nice error message at build time. The GCC function attribute error("message") was added in version 4.3, so we define a new macro __linktime_error(message) to expand to this for GCC-4.3 and later. This will give us an error diagnostic from the compiler on the line that fails. For other compilers __linktime_error(message) expands to nothing, and we have to be content with a link time error, but at least we will still get a build error. BUILD_BUG() expands to the undefined function __build_bug_failed() and will fail at link time if the compiler ever emits code for it. On GCC-4.3 and later, attribute((error())) is used so that the failure will be noted at compile time instead. Signed-off-by:David Daney <david.daney@cavium.com> Acked-by:
David Howells <dhowells@redhat.com> Signed-off-by:
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