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author | Mina Almasry <almasrymina@google.com> | 2019-11-30 17:56:54 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-12-01 12:59:08 -0800 |
commit | 5c9119542035dbbc61241ab8dc7feeac11fa82ca (patch) | |
tree | 059b96f3b2be7e3c25b24efaf36211ce11c45f0d /fs/hugetlbfs/inode.c | |
parent | 930668c34408ba983049322e04f13f03b6f1fafa (diff) | |
download | linux-5c9119542035dbbc61241ab8dc7feeac11fa82ca.tar.gz linux-5c9119542035dbbc61241ab8dc7feeac11fa82ca.tar.bz2 linux-5c9119542035dbbc61241ab8dc7feeac11fa82ca.zip |
hugetlb: region_chg provides only cache entry
Current behavior is that region_chg provides both a cache entry in
resv->region_cache, AND a placeholder entry in resv->regions.
region_add first tries to use the placeholder, and if it finds that the
placeholder has been deleted by a racing region_del call, it uses the
cache entry.
This behavior is completely unnecessary and is removed in this patch for
a couple of reasons:
1. region_add needs to either find a cached file_region entry in
resv->region_cache, or find an entry in resv->regions to expand. It
does not need both.
2. region_chg adding a placeholder entry in resv->regions opens up
a possible race with region_del, where region_chg adds a placeholder
region in resv->regions, and this region is deleted by a racing call
to region_del during region_chg execution or before region_add is
called. Removing the race makes the code easier to reason about and
maintain.
In addition, a follow up patch in another series that disables region
coalescing, which would be further complicated if the race with
region_del exists.
Link: http://lkml.kernel.org/r/20190919200428.188797-2-almasrymina@google.com
Signed-off-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/hugetlbfs/inode.c')
0 files changed, 0 insertions, 0 deletions