Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL 5.4 100/330] nfsd: Fix a soft lockup race in nfsd_file_mark_find_or_create() | Date | Thu, 17 Sep 2020 21:57:20 -0400 |
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From: Trond Myklebust <trondmy@gmail.com>
[ Upstream commit 90d2f1da832fd23290ef0c0d964d97501e5e8553 ]
If nfsd_file_mark_find_or_create() keeps winning the race for the nfsd_file_fsnotify_group->mark_mutex against nfsd_file_mark_put() then it can soft lock up, since fsnotify_add_inode_mark() ends up always finding an existing entry.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> --- fs/nfsd/filecache.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index 3007b8945d388..51c08ae79063c 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -133,9 +133,13 @@ nfsd_file_mark_find_or_create(struct nfsd_file *nf) struct nfsd_file_mark, nfm_mark)); mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex); - fsnotify_put_mark(mark); - if (likely(nfm)) + if (nfm) { + fsnotify_put_mark(mark); break; + } + /* Avoid soft lockup race with nfsd_file_mark_put() */ + fsnotify_destroy_mark(mark, nfsd_file_fsnotify_group); + fsnotify_put_mark(mark); } else mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex); -- 2.25.1
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