mm/swap: skip readahead only when swap slot cache is enabled
authorHuang Ying <ying.huang@intel.com>
Wed, 22 Feb 2017 23:45:46 +0000 (15:45 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 23 Feb 2017 00:41:30 +0000 (16:41 -0800)
commitba81f83842549871cbd7226fc11530dc464500bb
tree1722a6591e970b93efbbf51c39b6dd09f7832d6a
parent039939a65059852242c823ece685579370bc574f
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>
include/linux/swap_slots.h
mm/swap_slots.c
mm/swap_state.c