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authorHuang Ying <ying.huang@intel.com>2017-02-23 02:45:46 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-23 03:41:30 +0300
commitba81f83842549871cbd7226fc11530dc464500bb (patch)
tree1722a6591e970b93efbbf51c39b6dd09f7832d6a /include/linux/swap_slots.h
parent039939a65059852242c823ece685579370bc574f (diff)
downloadlinux-ba81f83842549871cbd7226fc11530dc464500bb.tar.xz
mm/swap: skip readahead only when swap slot cache is enabled
Because during swap off, a swap entry may have swap_map[] == SWAP_HAS_CACHE (for example, just allocated). If we return NULL in __read_swap_cache_async(), the swap off will abort. So when swap slot cache is disabled, (for swap off), we will wait for page to be put into swap cache in such race condition. This should not be a problem for swap slot cache, because swap slot cache should be drained after clearing swap_slot_cache_enabled. [ying.huang@intel.com: fix memory leak in __read_swap_cache_async()] Link: http://lkml.kernel.org/r/874lzt6znd.fsf@yhuang-dev.intel.com Link: http://lkml.kernel.org/r/5e2c5f6abe8e6eb0797408897b1bba80938e9b9d.1484082593.git.tim.c.chen@linux.intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> escreveu: Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/swap_slots.h')
-rw-r--r--include/linux/swap_slots.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/swap_slots.h b/include/linux/swap_slots.h
index ba5623b27c60..6ef92d17633d 100644
--- a/include/linux/swap_slots.h
+++ b/include/linux/swap_slots.h
@@ -25,4 +25,6 @@ void reenable_swap_slots_cache_unlock(void);
int enable_swap_slots_cache(void);
int free_swap_slot(swp_entry_t entry);
+extern bool swap_slot_cache_enabled;
+
#endif /* _LINUX_SWAP_SLOTS_H */