On Mon, Aug 22, 2022 at 9:28 AM Logan Gunthorpe [off-list ref] wrote:

On 2022-08-22 01:04, Song Liu wrote:

quoted

Could you please add some printk so that we know which condition triggered
handle_stripe_fill() here:

        if (s.to_read || s.non_overwrite
            || (s.to_write && s.failed)
            || (s.syncing && (s.uptodate + s.compute < disks))
            || s.replacing
            || s.expanding)
                handle_stripe_fill(sh, &s, disks);

This would help us narrow down to the exact condition. I guess it is
"(s.to_write && s.failed)", but I am not quite sure.

Ok, I hit this bug on a stripe and got these values for the call:

  to_read       = 0
  non_overwrite = 0
  to_write      = 0
  failed        = 1
  syncing       = 1
  uptodate      = 2
  compute       = 0
  disks         = 3
  replacing     = 0
  expanding     = 0

So it's actually the "(s.syncing && (s.uptodate + s.compute < disks))"
condition that is getting hit.

Thanks for the information! So the stripe is syncing. Could you please
try whether the following fixes the issue?

Thanks,
Song

diff --git i/drivers/md/raid5.c w/drivers/md/raid5.c
index 5cabdbbac48b..0580ebb11801 100644
--- i/drivers/md/raid5.c
+++ w/drivers/md/raid5.c

@@ -3952,7 +3952,7 @@ static void handle_stripe_fill(struct stripe_head *sh,
                 * back cache (prexor with orig_page, and then xor with
                 * page) in the read path
                 */
-               if (s->injournal && s->failed) {
+               if (s->to_read && s->injournal && s->failed) {
                        if (test_bit(STRIPE_R5C_CACHING, &sh->state))
                                r5c_make_stripe_write_out(sh);
                        goto out;