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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Cc: Mikulas Patocka <mpatocka@redhat.com>,
	Mike Snitzer <snitzer@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.6 342/638] dm: call the resume method on internal suspend
Date: Sun, 24 Mar 2024 18:56:19 -0400
Message-ID: <20240324230116.1348576-343-sashal@kernel.org>
In-Reply-To: <20240324230116.1348576-1-sashal@kernel.org>
References: <20240324230116.1348576-1-sashal@kernel.org>
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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 64a1f306c96c1..f945ee453457b 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2918,6 +2918,9 @@ static void __dm_internal_suspend(struct mapped_device *md, unsigned int suspend
 
 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)
@@ -2926,12 +2929,23 @@ 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