[PATCH 0/1] bcache fixes for Linux v5.3-rc4

[PATCH 0/1] bcache fixes for Linux v5.3-rc4

[Coly Li]

Hi Jens,

I have a bug report that is frequent happens in product environment,
the problem was introduced in Linux v5.2, we should have the fix in
in Linux v5.3.

Thanks in advance for taking this.

Coly Li 
---

Coly Li (1):
  bcache: Revert "bcache: use sysfs_match_string() instead of
    __sysfs_match_string()"

 drivers/md/bcache/sysfs.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

-- 
2.16.4

[PATCH 1/1] bcache: Revert "bcache: use sysfs_match_string() instead of __sysfs_match_string()"

[Coly Li]

This reverts commit 89e0341af082dbc170019f908846f4a424efc86b.

In drivers/md/bcache/sysfs.c:bch_snprint_string_list(), NULL pointer at
the end of list is necessary. Remove the NULL from last element of each
lists will cause the following panic,

[ 4340.455652] bcache: register_cache() registered cache device nvme0n1
[ 4340.464603] bcache: register_bdev() registered backing device sdk
[ 4421.587335] bcache: bch_cached_dev_run() cached dev sdk is running already
[ 4421.587348] bcache: bch_cached_dev_attach() Caching sdk as bcache0 on set 354e1d46-d99f-4d8b-870b-078b80dc88a6
[ 5139.247950] general protection fault: 0000 [#1] SMP NOPTI
[ 5139.247970] CPU: 9 PID: 5896 Comm: cat Not tainted 4.12.14-95.29-default #1 SLE12-SP4
[ 5139.247988] Hardware name: HPE ProLiant DL380 Gen10/ProLiant DL380 Gen10, BIOS U30 04/18/2019
[ 5139.248006] task: ffff888fb25c0b00 task.stack: ffff9bbacc704000
[ 5139.248021] RIP: 0010:string+0x21/0x70
[ 5139.248030] RSP: 0018:ffff9bbacc707bf0 EFLAGS: 00010286
[ 5139.248043] RAX: ffffffffa7e432e3 RBX: ffff8881c20da02a RCX: ffff0a00ffffff04
[ 5139.248058] RDX: 3f00656863616362 RSI: ffff8881c20db000 RDI: ffffffffffffffff
[ 5139.248075] RBP: ffff8881c20db000 R08: 0000000000000000 R09: ffff8881c20da02a
[ 5139.248090] R10: 0000000000000004 R11: 0000000000000000 R12: ffff9bbacc707c48
[ 5139.248104] R13: 0000000000000fd6 R14: ffffffffc0665855 R15: ffffffffc0665855
[ 5139.248119] FS:  00007faf253b8700(0000) GS:ffff88903f840000(0000) knlGS:0000000000000000
[ 5139.248137] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 5139.248149] CR2: 00007faf25395008 CR3: 0000000f72150006 CR4: 00000000007606e0
[ 5139.248164] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 5139.248179] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 5139.248193] PKRU: 55555554
[ 5139.248200] Call Trace:
[ 5139.248210]  vsnprintf+0x1fb/0x510
[ 5139.248221]  snprintf+0x39/0x40
[ 5139.248238]  bch_snprint_string_list.constprop.15+0x5b/0x90 [bcache]
[ 5139.248256]  __bch_cached_dev_show+0x44d/0x5f0 [bcache]
[ 5139.248270]  ? __alloc_pages_nodemask+0xb2/0x210
[ 5139.248284]  bch_cached_dev_show+0x2c/0x50 [bcache]
[ 5139.248297]  sysfs_kf_seq_show+0xbb/0x190
[ 5139.248308]  seq_read+0xfc/0x3c0
[ 5139.248317]  __vfs_read+0x26/0x140
[ 5139.248327]  vfs_read+0x87/0x130
[ 5139.248336]  SyS_read+0x42/0x90
[ 5139.248346]  do_syscall_64+0x74/0x160
[ 5139.248358]  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[ 5139.248370] RIP: 0033:0x7faf24eea370
[ 5139.248379] RSP: 002b:00007fff82d03f38 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[ 5139.248395] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007faf24eea370
[ 5139.248411] RDX: 0000000000020000 RSI: 00007faf25396000 RDI: 0000000000000003
[ 5139.248426] RBP: 00007faf25396000 R08: 00000000ffffffff R09: 0000000000000000
[ 5139.248441] R10: 000000007c9d4d41 R11: 0000000000000246 R12: 00007faf25396000
[ 5139.248456] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000fff
[ 5139.248892] Code: ff ff ff 0f 1f 80 00 00 00 00 49 89 f9 48 89 cf 48 c7 c0 e3 32 e4 a7 48 c1 ff 30 48 81 fa ff 0f 00 00 48 0f 46 d0 48 85 ff 74 45 <44> 0f b6 02 48 8d 42 01 45 84 c0 74 38 48 01 fa 4c 89 cf eb 0e

The simplest way to fix is to revert commit 89e0341af082 ("bcache: use
sysfs_match_string() instead of __sysfs_match_string()").

This bug was introduced in Linux v5.2, so this fix only applies to
Linux v5.2 is enough for stable tree maintainer.

Signed-off-by: Coly Li <colyli@suse.de>
Reported-by: Peifeng Lin <pflin@suse.com>
Cc: stable@vger.kernel.org
Cc: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
 drivers/md/bcache/sysfs.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 9f0826712845..e2059af90791 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -23,24 +23,28 @@ static const char * const bch_cache_modes[] = {
 	"writethrough",
 	"writeback",
 	"writearound",
-	"none"
+	"none",
+	NULL
 };
 
 /* Default is 0 ("auto") */
 static const char * const bch_stop_on_failure_modes[] = {
 	"auto",
-	"always"
+	"always",
+	NULL
 };
 
 static const char * const cache_replacement_policies[] = {
 	"lru",
 	"fifo",
-	"random"
+	"random",
+	NULL
 };
 
 static const char * const error_actions[] = {
 	"unregister",
-	"panic"
+	"panic",
+	NULL
 };
 
 write_attribute(attach);
@@ -338,7 +342,7 @@ STORE(__cached_dev)
 	}
 
 	if (attr == &sysfs_cache_mode) {
-		v = sysfs_match_string(bch_cache_modes, buf);
+		v = __sysfs_match_string(bch_cache_modes, -1, buf);
 		if (v < 0)
 			return v;
 
@@ -349,7 +353,7 @@ STORE(__cached_dev)
 	}
 
 	if (attr == &sysfs_stop_when_cache_set_failed) {
-		v = sysfs_match_string(bch_stop_on_failure_modes, buf);
+		v = __sysfs_match_string(bch_stop_on_failure_modes, -1, buf);
 		if (v < 0)
 			return v;
 
@@ -816,7 +820,7 @@ STORE(__bch_cache_set)
 			    0, UINT_MAX);
 
 	if (attr == &sysfs_errors) {
-		v = sysfs_match_string(error_actions, buf);
+		v = __sysfs_match_string(error_actions, -1, buf);
 		if (v < 0)
 			return v;
 
@@ -1088,7 +1092,7 @@ STORE(__bch_cache)
 	}
 
 	if (attr == &sysfs_cache_replacement_policy) {
-		v = sysfs_match_string(cache_replacement_policies, buf);
+		v = __sysfs_match_string(cache_replacement_policies, -1, buf);
 		if (v < 0)
 			return v;
 
-- 
2.16.4