• Wei Fang's avatar
    fs/dcache.c: avoid soft-lockup in dput() · 47be6184
    Wei Fang authored
    We triggered soft-lockup under stress test which
    open/access/write/close one file concurrently on more than
    five different CPUs:
    WARN: soft lockup - CPU#0 stuck for 11s! [who:30631]
    [<ffffffc0003986f8>] dput+0x100/0x298
    [<ffffffc00038c2dc>] terminate_walk+0x4c/0x60
    [<ffffffc00038f56c>] path_lookupat+0x5cc/0x7a8
    [<ffffffc00038f780>] filename_lookup+0x38/0xf0
    [<ffffffc000391180>] user_path_at_empty+0x78/0xd0
    [<ffffffc0003911f4>] user_path_at+0x1c/0x28
    [<ffffffc00037d4fc>] SyS_faccessat+0xb4/0x230
    ->d_lock trylock may failed many times because of concurrently
    operations, and dput() may execute a long time.
    Fix this by replacing cpu_relax() with cond_resched().
    dput() used to be sleepable, so make it sleepable again
    should be safe.
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarWei Fang <fangwei1@huawei.com>
    Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
dcache.c 94.4 KB