On Thu, Jun 25, 2020 at 2:22 AM Guoqing Jiang
<guoqing.jiang@xxxxxxxxxxxxxxx> wrote:
>
>
>
> On 6/24/20 1:58 AM, Song Liu wrote:
> > On Tue, Jun 16, 2020 at 2:25 AM Guoqing Jiang
> > <guoqing.jiang@xxxxxxxxxxxxxxx> wrote:
> >> We tried to only put the head sh of batch list to handle_list, then the
> >> handle_stripe doesn't handle other members in the batch list. However,
> >> we still got the calltrace in break_stripe_batch_list.
> >>
> >> [593764.644269] stripe state: 2003
> >> kernel: [593764.644299] ------------[ cut here ]------------
> >> kernel: [593764.644308] WARNING: CPU: 12 PID: 856 at drivers/md/raid5.c:4625 break_stripe_batch_list+0x203/0x240 [raid456]
> >> [...]
> >> kernel: [593764.644363] Call Trace:
> >> kernel: [593764.644370] handle_stripe+0x907/0x20c0 [raid456]
> >> kernel: [593764.644376] ? __wake_up_common_lock+0x89/0xc0
> >> kernel: [593764.644379] handle_active_stripes.isra.57+0x35f/0x570 [raid456]
> >> kernel: [593764.644382] ? raid5_wakeup_stripe_thread+0x96/0x1f0 [raid456]
> >> kernel: [593764.644385] raid5d+0x480/0x6a0 [raid456]
> >> kernel: [593764.644390] ? md_thread+0x11f/0x160
> >> kernel: [593764.644392] md_thread+0x11f/0x160
> >> kernel: [593764.644394] ? wait_woken+0x80/0x80
> >> kernel: [593764.644396] kthread+0xfc/0x130
> >> kernel: [593764.644398] ? find_pers+0x70/0x70
> >> kernel: [593764.644399] ? kthread_create_on_node+0x70/0x70
> >> kernel: [593764.644401] ret_from_fork+0x1f/0x30
> >>
> >> As we can see, the stripe was set with STRIPE_ACTIVE and STRIPE_HANDLE,
> >> and only handle_stripe could set those flags then return. And since the
> >> stipe was already in the batch list, we need to return earlier before
> >> set the two flags.
> >>
> >> And after dig a little about git history especially commit 3664847d95e6
> >> ("md/raid5: fix a race condition in stripe batch"), it seems the batched
> >> stipe still could be handled by handle_stipe, then handle_stipe needs to
> >> return earlier if clear_batch_ready to return true.
> >>
> >> Signed-off-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx>
> >> ---
> >> Another alternative would be just not warn if STRIPE_ACTIVE is valid for
> >> the batched list.
> >>
> >> What do you think?
> >>
> > This patch looks good to me (haven't tested yet). Let's try with this one.
>
> Ok, pls let me know if there is issue during test.
>
> And do you want a new patch to reflect which I clarified for the line
> number and kernel version?
That's not necessary. If needed, I will make some change when I apply the patch.
Thanks,
Song
