4.14-stable review patch. If anyone has any objections, please let me know.
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From: Artur Paszkiewicz artur.paszkiewicz@intel.com
commit b90f6ff080c52e2f05364210733df120e3c4e597 upstream.
Only MD_SB_CHANGE_PENDING should be used to wait for transition from clean to dirty. Checking also MD_SB_CHANGE_CLEAN is unnecessary and can race with e.g. md_do_sync(). This sporadically causes a hang when changing consistency policy during resync:
INFO: task mdadm:6183 blocked for more than 30 seconds. Not tainted 4.14.0-rc3+ #391 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. mdadm D12752 6183 6022 0x00000000 Call Trace: __schedule+0x93f/0x990 schedule+0x6b/0x90 md_allow_write+0x100/0x130 [md_mod] ? do_wait_intr_irq+0x90/0x90 resize_stripes+0x3a/0x5b0 [raid456] ? kernfs_fop_write+0xbe/0x180 raid5_change_consistency_policy+0xa6/0x200 [raid456] consistency_policy_store+0x2e/0x70 [md_mod] md_attr_store+0x90/0xc0 [md_mod] sysfs_kf_write+0x42/0x50 kernfs_fop_write+0x119/0x180 __vfs_write+0x28/0x110 ? rcu_sync_lockdep_assert+0x12/0x60 ? __sb_start_write+0x15a/0x1c0 ? vfs_write+0xa3/0x1a0 vfs_write+0xb4/0x1a0 SyS_write+0x49/0xa0 entry_SYSCALL_64_fastpath+0x18/0xad
Fixes: 2214c260c72b ("md: don't return -EAGAIN in md_allow_write for external metadata arrays") Signed-off-by: Artur Paszkiewicz artur.paszkiewicz@intel.com Signed-off-by: Shaohua Li shli@fb.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/md/md.c | 1 - 1 file changed, 1 deletion(-)
--- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8111,7 +8111,6 @@ void md_allow_write(struct mddev *mddev) sysfs_notify_dirent_safe(mddev->sysfs_state); /* wait for the dirty state to be recorded in the metadata */ wait_event(mddev->sb_wait, - !test_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags) && !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)); } else spin_unlock(&mddev->lock);