Mikulas Patocka <mpatocka@xxxxxxxxxx> writes:
> The commit 55ce74d4bfe1b9444436264c637f39a152d1e5ac (md/raid1: ensure
> device failure recorded before write request returns) is causing crash in
> the LVM2 testsuite test shell/lvchange-raid.sh. For me the crash is 100%
> reproducible.
>
> The reason for the crash is that the newly added code in raid1d moves the
> list from conf->bio_end_io_list to tmp, then tests if tmp is non-empty and
> then incorrectly pops the bio from conf->bio_end_io_list (which is empty
> because the list was alrady moved).
>
> Raid-10 has a similar bug.
Ouch. I can't have been thinking when I wrote that code!
Thanks for finding and fixing this. Patch will be sent to Linus in time
for next -rc.
Thanks,
NeilBrown
>
> Kernel Fault: Code=15 regs=000000006ccb8640 (Addr=0000000100000000)
> CPU: 3 PID: 1930 Comm: mdX_raid1 Not tainted 4.2.0-rc5-bisect+ #35
> task: 000000006cc1f258 ti: 000000006ccb8000 task.ti: 000000006ccb8000
>
> YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI
> PSW: 00001000000001001111111000001111 Not tainted
> r00-03 000000ff0804fe0f 000000001059d000 000000001059f818 000000007f16be38
> r04-07 000000001059d000 000000007f16be08 0000000000200200 0000000000000001
> r08-11 000000006ccb8260 000000007b7934d0 0000000000000001 0000000000000000
> r12-15 000000004056f320 0000000000000000 0000000000013dd0 0000000000000000
> r16-19 00000000f0d00ae0 0000000000000000 0000000000000000 0000000000000001
> r20-23 000000000800000f 0000000042200390 0000000000000000 0000000000000000
> r24-27 0000000000000001 000000000800000f 000000007f16be08 000000001059d000
> r28-31 0000000100000000 000000006ccb8560 000000006ccb8640 0000000000000000
> sr00-03 0000000000249800 0000000000000000 0000000000000000 0000000000249800
> sr04-07 0000000000000000 0000000000000000 0000000000000000 0000000000000000
>
> IASQ: 0000000000000000 0000000000000000 IAOQ: 000000001059f61c 000000001059f620
> IIR: 0f8010c6 ISR: 0000000000000000 IOR: 0000000100000000
> CPU: 3 CR30: 000000006ccb8000 CR31: 0000000000000000
> ORIG_R28: 000000001059d000
> IAOQ[0]: call_bio_endio+0x34/0x1a8 [raid1]
> IAOQ[1]: call_bio_endio+0x38/0x1a8 [raid1]
> RP(r2): raid_end_bio_io+0x88/0x168 [raid1]
> Backtrace:
> [<000000001059f818>] raid_end_bio_io+0x88/0x168 [raid1]
> [<00000000105a4f64>] raid1d+0x144/0x1640 [raid1]
> [<000000004017fd5c>] kthread+0x144/0x160
>
> Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> Fixes: 55ce74d4bfe1 ("md/raid1: ensure device failure recorded before write request returns.")
> Fixes: 95af587e95aa ("md/raid10: ensure device failure recorded before write request returns.")
>
> ---
> drivers/md/raid1.c | 4 ++--
> drivers/md/raid10.c | 4 ++--
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> Index: linux-2.6/drivers/md/raid1.c
> ===================================================================
> --- linux-2.6.orig/drivers/md/raid1.c 2015-10-01 21:10:05.000000000 +0200
> +++ linux-2.6/drivers/md/raid1.c 2015-10-01 21:10:58.000000000 +0200
> @@ -2437,8 +2437,8 @@ static void raid1d(struct md_thread *thr
> }
> spin_unlock_irqrestore(&conf->device_lock, flags);
> while (!list_empty(&tmp)) {
> - r1_bio = list_first_entry(&conf->bio_end_io_list,
> - struct r1bio, retry_list);
> + r1_bio = list_first_entry(&tmp, struct r1bio,
> + retry_list);
> list_del(&r1_bio->retry_list);
> raid_end_bio_io(r1_bio);
> }
> Index: linux-2.6/drivers/md/raid10.c
> ===================================================================
> --- linux-2.6.orig/drivers/md/raid10.c 2015-10-01 21:11:02.000000000 +0200
> +++ linux-2.6/drivers/md/raid10.c 2015-10-01 21:11:19.000000000 +0200
> @@ -2804,8 +2804,8 @@ static void raid10d(struct md_thread *th
> }
> spin_unlock_irqrestore(&conf->device_lock, flags);
> while (!list_empty(&tmp)) {
> - r10_bio = list_first_entry(&conf->bio_end_io_list,
> - struct r10bio, retry_list);
> + r10_bio = list_first_entry(&tmp, struct r10bio,
> + retry_list);
> list_del(&r10_bio->retry_list);
> raid_end_bio_io(r10_bio);
> }
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