Re: FAILED: patch "[PATCH] mm: revert "mm: shmem: fix data-race in shmem_getattr()"" failed to apply to 5.15-stable tree

[Sasha Levin <sashal@kernel.org>]

On Mon, Nov 18, 2024 at 10:14:18PM -0800, Hugh Dickins wrote:
>On Mon, 18 Nov 2024, Sasha Levin wrote:
>
>> [ Sasha's backport helper bot ]
>>
>> Hi,
>>
>> The upstream commit SHA1 provided is correct: d1aa0c04294e29883d65eac6c2f72fe95cc7c049
>>
>> WARNING: Author mismatch between patch and upstream commit:
>> Backport author: Hugh Dickins <hughd@google.com>
>> Commit author: Andrew Morton <akpm@linux-foundation.org>
>>
>> Commit in newer trees:
>>
>> |-----------------|----------------------------------------------|
>> | 6.11.y          |  Present (different SHA1: 285505dc512d)      |
>> | 6.6.y           |  Present (different SHA1: 552c02da3b0f)      |
>> | 6.1.y           |  Not found                                   |
>> | 5.15.y          |  Not found                                   |
>> |-----------------|----------------------------------------------|
>>
>> Note: The patch differs from the upstream commit:
>> ---
>> --- -	2024-11-18 22:45:37.221809852 -0500
>> +++ /tmp/tmp.gWYpEchJE1	2024-11-18 22:45:37.214517918 -0500
>> @@ -1,3 +1,12 @@
>> +For 5.15 please use this replacement patch:
>> +
>> +>From 975b740a6d720fdf478e9238b65fa96e9b5d631a Mon Sep 17 00:00:00 2001
>> +From: Andrew Morton <akpm@linux-foundation.org>
>> +Date: Fri, 15 Nov 2024 16:57:24 -0800
>> +Subject: [PATCH] mm: revert "mm: shmem: fix data-race in shmem_getattr()"
>> +
>> +commit d1aa0c04294e29883d65eac6c2f72fe95cc7c049 upstream.
>> +
>>  Revert d949d1d14fa2 ("mm: shmem: fix data-race in shmem_getattr()") as
>>  suggested by Chuck [1].  It is causing deadlocks when accessing tmpfs over
>>  NFS.
>> @@ -13,21 +22,25 @@
>>  Cc: Yu Zhao <yuzhao@google.com>
>>  Cc: <stable@vger.kernel.org>
>>  Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
>> +Signed-off-by: Hugh Dickins <hughd@google.com>
>>  ---
>>   mm/shmem.c | 2 --
>>   1 file changed, 2 deletions(-)
>>
>>  diff --git a/mm/shmem.c b/mm/shmem.c
>> -index e87f5d6799a7b..568bb290bdce3 100644
>> +index cdb169348ba9..663fb117cd87 100644
>>  --- a/mm/shmem.c
>>  +++ b/mm/shmem.c
>> -@@ -1166,9 +1166,7 @@ static int shmem_getattr(struct mnt_idmap *idmap,
>> - 	stat->attributes_mask |= (STATX_ATTR_APPEND |
>> - 			STATX_ATTR_IMMUTABLE |
>> - 			STATX_ATTR_NODUMP);
>> +@@ -1077,9 +1077,7 @@ static int shmem_getattr(struct user_namespace *mnt_userns,
>> + 		shmem_recalc_inode(inode);
>> + 		spin_unlock_irq(&info->lock);
>> + 	}
>>  -	inode_lock_shared(inode);
>> - 	generic_fillattr(idmap, request_mask, inode, stat);
>> + 	generic_fillattr(&init_user_ns, inode, stat);
>>  -	inode_unlock_shared(inode);
>>
>> - 	if (shmem_huge_global_enabled(inode, 0, 0, false, NULL, 0))
>> + 	if (shmem_is_huge(NULL, inode, 0))
>>   		stat->blksize = HPAGE_PMD_SIZE;
>> +--
>> +2.47.0.338.g60cca15819-goog
>> +
>> ---
>>
>> Results of testing on various branches:
>>
>> | Branch                    | Patch Apply | Build Test |
>> |---------------------------|-------------|------------|
>> | stable/linux-5.15.y       |  Success    |  Failed    |
>>
>> Build Errors:
>> Build error for stable/linux-5.15.y:
>
>Sorry, I've not received a mail like this before,
>and don't know what action to take in response to it.
>
>I notice that this 5.15 one says Build Test Failed: that's a surprise,
>it built for me on 5.15.173; but perhaps something has gone into the
>queue since then which causes it not to build?
>
>Or perhaps this is just a bot mail to be ignored?

It's something we're trying out to improve our efficiency around picking
up backports from the mailing list.

Given the bot failed to attach a build log, it seems like an issue with
the bot that I'll go fix. Sorry for the noise.

-- 
Thanks,
Sasha