[PATCH 5.15 155/317] dm: call the resume method on internal suspend

Sasha Levin
2024-03-24T23:37:32Z

From: Mikulas Patocka <mpatocka@redhat.com>

[ Upstream commit 65e8fbde64520001abf1c8d0e573561b4746ef38 ]

There is this reported crash when experimenting with the lvm2 testsuite.
The list corruption is caused by the fact that the postsuspend and resume
methods were not paired correctly; there were two consecutive calls to the
origin_postsuspend function. The second call attempts to remove the
"hash_list" entry from a list, while it was already removed by the first
call.

Fix __dm_internal_resume so that it calls the preresume and resume
methods of the table's targets.

If a preresume method of some target fails, we are in a tricky situation.
We can't return an error because dm_internal_resume isn't supposed to
return errors. We can't return success, because then the "resume" and
"postsuspend" methods would not be paired correctly. So, we set the
DMF_SUSPENDED flag and we fake normal suspend - it may confuse userspace
tools, but it won't cause a kernel crash.

------------[ cut here ]------------
kernel BUG at lib/list_debug.c:56!
invalid opcode: 0000 [#1] PREEMPT SMP
CPU: 1 PID: 8343 Comm: dmsetup Not tainted 6.8.0-rc6 #4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
RIP: 0010:__list_del_entry_valid_or_report+0x77/0xc0
<snip>
RSP: 0018:ffff8881b831bcc0 EFLAGS: 00010282
RAX: 000000000000004e RBX: ffff888143b6eb80 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffffffff819053d0 RDI: 00000000ffffffff
RBP: ffff8881b83a3400 R08: 00000000fffeffff R09: 0000000000000058
R10: 0000000000000000 R11: ffffffff81a24080 R12: 0000000000000001
R13: ffff88814538e000 R14: ffff888143bc6dc0 R15: ffffffffa02e4bb0
FS: 00000000f7c0f780(0000) GS:ffff8893f0a40000(0000) knlGS:0000000000000000
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000057fb5000 CR3: 0000000143474000 CR4: 00000000000006b0
Call Trace:
<TASK>
? die+0x2d/0x80
? do_trap+0xeb/0xf0
? __list_del_entry_valid_or_report+0x77/0xc0
? do_error_trap+0x60/0x80
? __list_del_entry_valid_or_report+0x77/0xc0
? exc_invalid_op+0x49/0x60
? __list_del_entry_valid_or_report+0x77/0xc0
? asm_exc_invalid_op+0x16/0x20
? table_deps+0x1b0/0x1b0 [dm_mod]
? __list_del_entry_valid_or_report+0x77/0xc0
origin_postsuspend+0x1a/0x50 [dm_snapshot]
dm_table_postsuspend_targets+0x34/0x50 [dm_mod]
dm_suspend+0xd8/0xf0 [dm_mod]
dev_suspend+0x1f2/0x2f0 [dm_mod]
? table_deps+0x1b0/0x1b0 [dm_mod]
ctl_ioctl+0x300/0x5f0 [dm_mod]
dm_compat_ctl_ioctl+0x7/0x10 [dm_mod]
__x64_compat_sys_ioctl+0x104/0x170
do_syscall_64+0x184/0x1b0
entry_SYSCALL_64_after_hwframe+0x46/0x4e
RIP: 0033:0xf7e6aead
<snip>
---[ end trace 0000000000000000 ]---

Fixes: ffcc39364160 ("dm: enhance internal suspend and resume interface")
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/dm.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index d6285a23dc3ed..fd9bb8b53219a 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2641,6 +2641,9 @@ static void __dm_internal_suspend(struct mapped_device *md, unsigned suspend_fla

static void __dm_internal_resume(struct mapped_device *md)
{
+ int r;
+ struct dm_table *map;
+
BUG_ON(!md->internal_suspend_count);

if (--md->internal_suspend_count)
@@ -2649,12 +2652,23 @@ static void __dm_internal_resume(struct mapped_device *md)
if (dm_suspended_md(md))
goto done; /* resume from nested suspend */

- /*
- * NOTE: existing callers don't need to call dm_table_resume_targets
- * (which may fail -- so best to avoid it for now by passing NULL map)
- */
- (void) __dm_resume(md, NULL);
-
+ map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
+ r = __dm_resume(md, map);
+ if (r) {
+ /*
+ * If a preresume method of some target failed, we are in a
+ * tricky situation. We can't return an error to the caller. We
+ * can't fake success because then the "resume" and
+ * "postsuspend" methods would not be paired correctly, and it
+ * would break various targets, for example it would cause list
+ * corruption in the "origin" target.
+ *
+ * So, we fake normal suspend here, to make sure that the
+ * "resume" and "postsuspend" methods will be paired correctly.
+ */
+ DMERR("Preresume method failed: %d", r);
+ set_bit(DMF_SUSPENDED, &md->flags);
+ }
done:
clear_bit(DMF_SUSPENDED_INTERNALLY, &md->flags);
smp_mb__after_atomic();
--
2.43.0