linux-kernel - Re: [PATCH] mm/slub: fix to return errno if kmalloc() fails

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Date:   Wed, 31 Aug 2022 11:09:09 +0800
From:   Muchun Song <muchun.song@...ux.dev>
To:     Chao Yu <chao@...nel.org>
Cc:     Linux MM <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, jaegeuk@...nel.org,
        Chao Yu <chao.yu@...o.com>, stable@...nel.org,
        syzbot+81684812ea68216e08c5@...kaller.appspotmail.com
Subject: Re: [PATCH] mm/slub: fix to return errno if kmalloc() fails



> On Aug 30, 2022, at 22:10, Chao Yu <chao@...nel.org> wrote:
> 
> From: Chao Yu <chao.yu@...o.com>
> 
> In create_unique_id(), kmalloc(, GFP_KERNEL) can fail due to
> out-of-memory, if it fails, return errno correctly rather than
> triggering panic via BUG_ON();

I tend to agree with you. A mount operation shouldn’t panic the
kernel.

> 
> kernel BUG at mm/slub.c:5893!
> Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
> 
> Call trace:
> sysfs_slab_add+0x258/0x260 mm/slub.c:5973
> __kmem_cache_create+0x60/0x118 mm/slub.c:4899
> create_cache mm/slab_common.c:229 [inline]
> kmem_cache_create_usercopy+0x19c/0x31c mm/slab_common.c:335
> kmem_cache_create+0x1c/0x28 mm/slab_common.c:390
> f2fs_kmem_cache_create fs/f2fs/f2fs.h:2766 [inline]
> f2fs_init_xattr_caches+0x78/0xb4 fs/f2fs/xattr.c:808
> f2fs_fill_super+0x1050/0x1e0c fs/f2fs/super.c:4149
> mount_bdev+0x1b8/0x210 fs/super.c:1400
> f2fs_mount+0x44/0x58 fs/f2fs/super.c:4512
> legacy_get_tree+0x30/0x74 fs/fs_context.c:610
> vfs_get_tree+0x40/0x140 fs/super.c:1530
> do_new_mount+0x1dc/0x4e4 fs/namespace.c:3040
> path_mount+0x358/0x914 fs/namespace.c:3370
> do_mount fs/namespace.c:3383 [inline]
> __do_sys_mount fs/namespace.c:3591 [inline]
> __se_sys_mount fs/namespace.c:3568 [inline]
> __arm64_sys_mount+0x2f8/0x408 fs/namespace.c:3568
> 
> Cc: <stable@...nel.org>
> Reported-by: syzbot+81684812ea68216e08c5@...kaller.appspotmail.com
> Signed-off-by: Chao Yu <chao.yu@...o.com>

Reviewed-by: Muchun Song <songmuchun@...edance.com>

Thanks.