| Message ID | 51539879-e1ca-fde3-b8b4-8934ddedcbc@redhat.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
| Series | MD fixes for the LVM2 testsuite | expand |
On Wed, Jan 17, 2024 at 10:22 AM Mikulas Patocka <mpatocka@redhat.com> wrote: > > RCU protection was removed in the commit 2d32777d60de ("raid1: remove rcu > protection to access rdev from conf"). > > However, the code in fix_read_error does rcu_dereference outside > rcu_read_lock - this triggers the following warning. The warning is > triggered by a LVM2 test shell/integrity-caching.sh. > > This commit removes rcu_dereference. > > ============================= > WARNING: suspicious RCU usage > 6.7.0 #2 Not tainted > ----------------------------- > drivers/md/raid1.c:2265 suspicious rcu_dereference_check() usage! > > other info that might help us debug this: > > rcu_scheduler_active = 2, debug_locks = 1 > no locks held by mdX_raid1/1859. > > stack backtrace: > CPU: 2 PID: 1859 Comm: mdX_raid1 Not tainted 6.7.0 #2 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 > Call Trace: > <TASK> > dump_stack_lvl+0x60/0x70 > lockdep_rcu_suspicious+0x153/0x1b0 > raid1d+0x1732/0x1750 [raid1] > ? lock_acquire+0x9f/0x270 > ? finish_wait+0x3d/0x80 > ? md_thread+0xf7/0x130 [md_mod] > ? lock_release+0xaa/0x230 > ? md_register_thread+0xd0/0xd0 [md_mod] > md_thread+0xa0/0x130 [md_mod] > ? housekeeping_test_cpu+0x30/0x30 > kthread+0xdc/0x110 > ? kthread_complete_and_exit+0x20/0x20 > ret_from_fork+0x28/0x40 > ? kthread_complete_and_exit+0x20/0x20 > ret_from_fork_asm+0x11/0x20 > </TASK> > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > Fixes: ca294b34aaf3 ("md/raid1: support read error check") This makes sense to me. Li Nan, please review this fix. Thanks, Song > > --- > drivers/md/raid1.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > Index: linux-2.6/drivers/md/raid1.c > =================================================================== > --- linux-2.6.orig/drivers/md/raid1.c > +++ linux-2.6/drivers/md/raid1.c > @@ -2262,7 +2262,7 @@ static void fix_read_error(struct r1conf > int sectors = r1_bio->sectors; > int read_disk = r1_bio->read_disk; > struct mddev *mddev = conf->mddev; > - struct md_rdev *rdev = rcu_dereference(conf->mirrors[read_disk].rdev); > + struct md_rdev *rdev = conf->mirrors[read_disk].rdev; > > if (exceed_read_errors(mddev, rdev)) { > r1_bio->bios[r1_bio->read_disk] = IO_BLOCKED; >
在 2024/01/18 2:22, Mikulas Patocka 写道: > RCU protection was removed in the commit 2d32777d60de ("raid1: remove rcu > protection to access rdev from conf"). > > However, the code in fix_read_error does rcu_dereference outside > rcu_read_lock - this triggers the following warning. The warning is > triggered by a LVM2 test shell/integrity-caching.sh. > > This commit removes rcu_dereference. > > ============================= > WARNING: suspicious RCU usage > 6.7.0 #2 Not tainted > ----------------------------- > drivers/md/raid1.c:2265 suspicious rcu_dereference_check() usage! > > other info that might help us debug this: > > rcu_scheduler_active = 2, debug_locks = 1 > no locks held by mdX_raid1/1859. > > stack backtrace: > CPU: 2 PID: 1859 Comm: mdX_raid1 Not tainted 6.7.0 #2 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 > Call Trace: > <TASK> > dump_stack_lvl+0x60/0x70 > lockdep_rcu_suspicious+0x153/0x1b0 > raid1d+0x1732/0x1750 [raid1] > ? lock_acquire+0x9f/0x270 > ? finish_wait+0x3d/0x80 > ? md_thread+0xf7/0x130 [md_mod] > ? lock_release+0xaa/0x230 > ? md_register_thread+0xd0/0xd0 [md_mod] > md_thread+0xa0/0x130 [md_mod] > ? housekeeping_test_cpu+0x30/0x30 > kthread+0xdc/0x110 > ? kthread_complete_and_exit+0x20/0x20 > ret_from_fork+0x28/0x40 > ? kthread_complete_and_exit+0x20/0x20 > ret_from_fork_asm+0x11/0x20 > </TASK> > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > Fixes: ca294b34aaf3 ("md/raid1: support read error check") LGTM Reviewed-by: Yu Kuai <yukuai3@huawei.com> > > --- > drivers/md/raid1.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > Index: linux-2.6/drivers/md/raid1.c > =================================================================== > --- linux-2.6.orig/drivers/md/raid1.c > +++ linux-2.6/drivers/md/raid1.c > @@ -2262,7 +2262,7 @@ static void fix_read_error(struct r1conf > int sectors = r1_bio->sectors; > int read_disk = r1_bio->read_disk; > struct mddev *mddev = conf->mddev; > - struct md_rdev *rdev = rcu_dereference(conf->mirrors[read_disk].rdev); > + struct md_rdev *rdev = conf->mirrors[read_disk].rdev; > > if (exceed_read_errors(mddev, rdev)) { > r1_bio->bios[r1_bio->read_disk] = IO_BLOCKED; > > . >
On Wed, Jan 17, 2024 at 5:56 PM Yu Kuai <yukuai1@huaweicloud.com> wrote: > [...] > > </TASK> > > > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > > Fixes: ca294b34aaf3 ("md/raid1: support read error check") > > LGTM > Reviewed-by: Yu Kuai <yukuai3@huawei.com> Applied patch 7 to md-6.8 branch. Thanks, Song
Index: linux-2.6/drivers/md/raid1.c =================================================================== --- linux-2.6.orig/drivers/md/raid1.c +++ linux-2.6/drivers/md/raid1.c @@ -2262,7 +2262,7 @@ static void fix_read_error(struct r1conf int sectors = r1_bio->sectors; int read_disk = r1_bio->read_disk; struct mddev *mddev = conf->mddev; - struct md_rdev *rdev = rcu_dereference(conf->mirrors[read_disk].rdev); + struct md_rdev *rdev = conf->mirrors[read_disk].rdev; if (exceed_read_errors(mddev, rdev)) { r1_bio->bios[r1_bio->read_disk] = IO_BLOCKED;
RCU protection was removed in the commit 2d32777d60de ("raid1: remove rcu protection to access rdev from conf"). However, the code in fix_read_error does rcu_dereference outside rcu_read_lock - this triggers the following warning. The warning is triggered by a LVM2 test shell/integrity-caching.sh. This commit removes rcu_dereference. ============================= WARNING: suspicious RCU usage 6.7.0 #2 Not tainted ----------------------------- drivers/md/raid1.c:2265 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 no locks held by mdX_raid1/1859. stack backtrace: CPU: 2 PID: 1859 Comm: mdX_raid1 Not tainted 6.7.0 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x60/0x70 lockdep_rcu_suspicious+0x153/0x1b0 raid1d+0x1732/0x1750 [raid1] ? lock_acquire+0x9f/0x270 ? finish_wait+0x3d/0x80 ? md_thread+0xf7/0x130 [md_mod] ? lock_release+0xaa/0x230 ? md_register_thread+0xd0/0xd0 [md_mod] md_thread+0xa0/0x130 [md_mod] ? housekeeping_test_cpu+0x30/0x30 kthread+0xdc/0x110 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x28/0x40 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork_asm+0x11/0x20 </TASK> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Fixes: ca294b34aaf3 ("md/raid1: support read error check") --- drivers/md/raid1.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)