Patch "Revert "md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d"" has been added to the 6.1-stable tree

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This is a note to let you know that I've just added the patch titled

    Revert "md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d"

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     revert-md-raid5-wait-for-md_sb_change_pending-in-raid5d.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From bed9e27baf52a09b7ba2a3714f1e24e17ced386d Mon Sep 17 00:00:00 2001
From: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Date: Wed, 8 Nov 2023 10:22:16 -0800
Subject: Revert "md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d"

From: Junxiao Bi <junxiao.bi@xxxxxxxxxx>

commit bed9e27baf52a09b7ba2a3714f1e24e17ced386d upstream.

This reverts commit 5e2cf333b7bd5d3e62595a44d598a254c697cd74.

That commit introduced the following race and can cause system hung.

 md_write_start:             raid5d:
 // mddev->in_sync == 1
 set "MD_SB_CHANGE_PENDING"
                            // running before md_write_start wakeup it
                             waiting "MD_SB_CHANGE_PENDING" cleared
                             >>>>>>>>> hung
 wakeup mddev->thread
 ...
 waiting "MD_SB_CHANGE_PENDING" cleared
 >>>> hung, raid5d should clear this flag
 but get hung by same flag.

The issue reverted commit fixing is fixed by last patch in a new way.

Fixes: 5e2cf333b7bd ("md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d")
Cc: stable@xxxxxxxxxxxxxxx # v5.19+
Signed-off-by: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20231108182216.73611-2-junxiao.bi@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/md/raid5.c |   12 ------------
 1 file changed, 12 deletions(-)

--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -36,7 +36,6 @@
  */
 
 #include <linux/blkdev.h>
-#include <linux/delay.h>
 #include <linux/kthread.h>
 #include <linux/raid/pq.h>
 #include <linux/async_tx.h>
@@ -6833,18 +6832,7 @@ static void raid5d(struct md_thread *thr
 			spin_unlock_irq(&conf->device_lock);
 			md_check_recovery(mddev);
 			spin_lock_irq(&conf->device_lock);
-
-			/*
-			 * Waiting on MD_SB_CHANGE_PENDING below may deadlock
-			 * seeing md_check_recovery() is needed to clear
-			 * the flag when using mdmon.
-			 */
-			continue;
 		}
-
-		wait_event_lock_irq(mddev->sb_wait,
-			!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags),
-			conf->device_lock);
 	}
 	pr_debug("%d stripes handled\n", handled);
 


Patches currently in stable-queue which might be from junxiao.bi@xxxxxxxxxx are

queue-6.1/revert-md-raid5-wait-for-md_sb_change_pending-in-raid5d.patch




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