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KOSAKI Motohiro authored
Shaohua Li reported parallel file copy on tmpfs can lead to OOM killer. This is regression of caused by commit 9ff473b9 ("vmscan: evict streaming IO first"). Wow, It is 2 years old patch! Currently, tmpfs file cache is inserted active list at first. This means that the insertion doesn't only increase numbers of pages in anon LRU, but it also reduces anon scanning ratio. Therefore, vmscan will get totally confused. It scans almost only file LRU even though the system has plenty unused tmpfs pages. Historically, lru_cache_add_active_anon() was used for two reasons. 1) Intend to priotize shmem page rather than regular file cache. 2) Intend to avoid reclaim priority inversion of used once pages. But we've lost both motivation because (1) Now we have separate anon and file LRU list. then, to insert active list doesn't help such priotize. (2) In past, one pte access bit will cause page activation. then to insert inactive list with pte access bit mean higher priority than to insert active list. Its priority inversion may lead to uninteded lru chun. but it was already solved by commit 64574746 (vmscan: detect mapped file pages used only once). (Thanks Hannes, you are great!) Thus, now we can use lru_cache_add_anon() instead. Signed-off-by:
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reported-by:
Shaohua Li <shaohua.li@intel.com> Reviewed-by:
Wu Fengguang <fengguang.wu@intel.com> Reviewed-by:
Johannes Weiner <hannes@cmpxchg.org> Reviewed-by:
Rik van Riel <riel@redhat.com> Reviewed-by:
Minchan Kim <minchan.kim@gmail.com> Acked-by:
Hugh Dickins <hughd@google.com> Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br> Cc: <stable@kernel.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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