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authorNeilBrown <neilb@suse.com>2017-08-08 16:56:36 +1000
committerShaohua Li <shli@fb.com>2017-08-08 07:42:35 -0700
commit33182d15c6bf182f7ae32a66ea4a547d979cd6d7 (patch)
tree3474674380ae8c826eb5f19d36da994464535345 /drivers/md
parent16f73eb02d7e1765ccab3d2018e0bd98eb93d973 (diff)
md: always clear ->safemode when md_check_recovery gets the mddev lock.
If ->safemode == 1, md_check_recovery() will try to get the mddev lock and perform various other checks. If mddev->in_sync is zero, it will call set_in_sync, and clear ->safemode. However if mddev->in_sync is not zero, ->safemode will not be cleared. When md_check_recovery() drops the mddev lock, the thread is woken up again. Normally it would just check if there was anything else to do, find nothing, and go to sleep. However as ->safemode was not cleared, it will take the mddev lock again, then wake itself up when unlocking. This results in an infinite loop, repeatedly calling md_check_recovery(), which RCU or the soft-lockup detector will eventually complain about. Prior to commit 4ad23a976413 ("MD: use per-cpu counter for writes_pending"), safemode would only be set to one when the writes_pending counter reached zero, and would be cleared again when writes_pending is incremented. Since that patch, safemode is set more freely, but is not reliably cleared. So in md_check_recovery() clear ->safemode before checking ->in_sync. Fixes: 4ad23a976413 ("MD: use per-cpu counter for writes_pending") Cc: stable@vger.kernel.org (4.12+) Reported-by: Dominik Brodowski <linux@dominikbrodowski.net> Reported-by: David R <david@unsolicited.net> Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/md.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c
index c99634612fc4..d84aceede1cb 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8656,6 +8656,9 @@ void md_check_recovery(struct mddev *mddev)
if (mddev_trylock(mddev)) {
int spares = 0;
+ if (mddev->safemode == 1)
+ mddev->safemode = 0;
+
if (mddev->ro) {
struct md_rdev *rdev;
if (!mddev->external && mddev->in_sync)