xfs: Timely free truncated dirty pages
Subsystems (2)
PATCH v2 1/1 xfs: Timely free truncated dirty pages
Commit 99579ccec4e2 "xfs: skip dirty pages in ->releasepage()" started to skip dirty pages in xfs_vm_releasepage() which also has the effect that if a dirty page is truncated, it does not get freed by block_invalidatepage() and is lingering in LRU list waiting for reclaim. So a simple loop like:
while true; do
dd if=/dev/zero of=file bs=1M count=100 rm file
done
will keep using more and more memory until we hit low watermarks and start pagecache reclaim which will eventually reclaim also the truncate pages. Keeping these truncated (and thus never usable) pages in memory is just a waste of memory, is unnecessarily stressing page cache reclaim, and reportedly also leads to anonymous mmap(2) returning ENOMEM prematurely.
So instead of just skipping dirty pages in xfs_vm_releasepage(), return to old behavior of skipping them only if they have delalloc or unwritten buffers and fix the spurious warnings by warning only if the page is clean.
--- fs/xfs/xfs_aops.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)
fs/xfs/xfs_aops.c +11 -8
@@ -1152,19 +1152,22 @@ xfs_vm_releasepage(* block_invalidatepage() can send pages that are still marked dirty * but otherwise have invalidated buffers. * -* We've historically freed buffers on the latter. Instead, quietly -* filter out all dirty pages to avoid spurious buffer state warnings. -* This can likely be removed once shrink_active_list() is fixed. +* We want to release the latter to avoid unnecessary buildup of the +* LRU, skip the former and warn if we've left any lingering +* delalloc/unwritten buffers on clean pages. Skip pages with delalloc +* or unwritten buffers and warn if the page is not dirty. Otherwise +* try to release the buffers. */ -if (PageDirty (page)) -return 0 ; -xfs_count_page_state (page, &delalloc, &unwritten); -if (WARN_ON_ONCE (delalloc)) +if (delalloc) { +WARN_ON_ONCE (!PageDirty (page));return 0 ; -if (WARN_ON_ONCE (unwritten)) + } +if (unwritten) { +WARN_ON_ONCE (!PageDirty (page));return 0 ; + }return try_to_free_buffers (page); }
Signature · 1 line
2.10.2
Quoted 23 lines · Jan Kara
Commit
99579ccec4e2"xfs: skip dirty pages in ->releasepage()" started to skip dirty pages inxfs_vm_releasepage()which also has the effect that if a dirty page is truncated, it does not get freed byblock_invalidatepage()and is lingering in LRU list waiting for reclaim. So a simple loop like:while true; do
dd if=/dev/zero of=file bs=1M count=100 rm filedone
will keep using more and more memory until we hit low watermarks and start pagecache reclaim which will eventually reclaim also the truncate pages. Keeping these truncated (and thus never usable) pages in memory is just a waste of memory, is unnecessarily stressing page cache reclaim, and reportedly also leads to anonymous mmap(2) returning ENOMEM prematurely.
So instead of just skipping dirty pages in
xfs_vm_releasepage(), return to old behavior of skipping them only if they have delalloc or unwritten buffers and fix the spurious warnings by warning only if the page is clean.
Quoted 7 lines
CC Brian Foster <[email protected]>CC Vlastimil Babka <[email protected]>Reported-by Petr Tůma <[email protected]>Fixes 99579ccec4e271c3d4d4e7c946058766812afdabSigned-off-by Jan Kara <[email protected]>---
Quoted 45 lines
fs/xfs/xfs_aops.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)fs/xfs/xfs_aops.c +11
-8@@ -1152,19 +1152,22 @@ xfs_vm_releasepage(* block_invalidatepage() can send pages that are still marked dirty * but otherwise have invalidated buffers. * -* We've historically freed buffers on the latter. Instead, quietly -* filter out all dirty pages to avoid spurious buffer state warnings. -* This can likely be removed once shrink_active_list() is fixed. +* We want to release the latter to avoid unnecessary buildup of the +* LRU, skip the former and warn if we've left any lingering +* delalloc/unwritten buffers on clean pages. Skip pages with delalloc +* or unwritten buffers and warn if the page is not dirty. Otherwise +* try to release the buffers. */ -if (PageDirty (page)) -return 0 ; -xfs_count_page_state (page, &delalloc, &unwritten); -if (WARN_ON_ONCE (delalloc)) +if (delalloc) { +WARN_ON_ONCE (!PageDirty (page));return 0 ; -if (WARN_ON_ONCE (unwritten)) + } +if (unwritten) { +WARN_ON_ONCE (!PageDirty (page));return 0 ; + }return try_to_free_buffers (page); }Signature · 6 lines
2.10.2 -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
Darrick J. Wong
AppliedQuoted 23 lines · Jan Kara
Commit
99579ccec4e2"xfs: skip dirty pages in ->releasepage()" started to skip dirty pages inxfs_vm_releasepage()which also has the effect that if a dirty page is truncated, it does not get freed byblock_invalidatepage()and is lingering in LRU list waiting for reclaim. So a simple loop like:while true; do
dd if=/dev/zero of=file bs=1M count=100 rm filedone
will keep using more and more memory until we hit low watermarks and start pagecache reclaim which will eventually reclaim also the truncate pages. Keeping these truncated (and thus never usable) pages in memory is just a waste of memory, is unnecessarily stressing page cache reclaim, and reportedly also leads to anonymous mmap(2) returning ENOMEM prematurely.
So instead of just skipping dirty pages in
xfs_vm_releasepage(), return to old behavior of skipping them only if they have delalloc or unwritten buffers and fix the spurious warnings by warning only if the page is clean.
Quoted 6 lines
CC Brian Foster <[email protected]>CC Vlastimil Babka <[email protected]>Reported-by Petr Tůma <[email protected]>Fixes 99579ccec4e271c3d4d4e7c946058766812afdabSigned-off-by Jan Kara <[email protected]>
Applied, thanks.
--D
Quoted 46 lines
--- fs/xfs/xfs_aops.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)fs/xfs/xfs_aops.c +11
-8@@ -1152,19 +1152,22 @@ xfs_vm_releasepage(* block_invalidatepage() can send pages that are still marked dirty * but otherwise have invalidated buffers. * -* We've historically freed buffers on the latter. Instead, quietly -* filter out all dirty pages to avoid spurious buffer state warnings. -* This can likely be removed once shrink_active_list() is fixed. +* We want to release the latter to avoid unnecessary buildup of the +* LRU, skip the former and warn if we've left any lingering +* delalloc/unwritten buffers on clean pages. Skip pages with delalloc +* or unwritten buffers and warn if the page is not dirty. Otherwise +* try to release the buffers. */ -if (PageDirty (page)) -return 0 ; -xfs_count_page_state (page, &delalloc, &unwritten); -if (WARN_ON_ONCE (delalloc)) +if (delalloc) { +WARN_ON_ONCE (!PageDirty (page));return 0 ; -if (WARN_ON_ONCE (unwritten)) + } +if (unwritten) { +WARN_ON_ONCE (!PageDirty (page));return 0 ; + }return try_to_free_buffers (page); }Signature · 6 lines
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