From: "Theodore Ts'o" <tytso@mit.edu>
To: Jan Kara <jack@suse.cz>
Cc: linux-ext4@vger.kernel.org
Subject: Re: [PATCH] ext4: Add checks to xattr code that we have appropriate reclaim context
Date: Fri, 5 Mar 2021 09:29:35 -0500 [thread overview]
Message-ID: <YEJAT+4flwcxSrXY@mit.edu> (raw)
In-Reply-To: <20210222171626.21884-1-jack@suse.cz>
On Mon, Feb 22, 2021 at 06:16:26PM +0100, Jan Kara wrote:
> Syzbot is reporting that ext4 can enter fs reclaim from kvmalloc() while
> the transaction is started like:
>
> fs_reclaim_acquire+0x117/0x150 mm/page_alloc.c:4340
> might_alloc include/linux/sched/mm.h:193 [inline]
> slab_pre_alloc_hook mm/slab.h:493 [inline]
> slab_alloc_node mm/slub.c:2817 [inline]
> __kmalloc_node+0x5f/0x430 mm/slub.c:4015
> kmalloc_node include/linux/slab.h:575 [inline]
> kvmalloc_node+0x61/0xf0 mm/util.c:587
> kvmalloc include/linux/mm.h:781 [inline]
> ext4_xattr_inode_cache_find fs/ext4/xattr.c:1465 [inline]
> ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1508 [inline]
> ext4_xattr_set_entry+0x1ce6/0x3780 fs/ext4/xattr.c:1649
> ext4_xattr_ibody_set+0x78/0x2b0 fs/ext4/xattr.c:2224
> ext4_xattr_set_handle+0x8f4/0x13e0 fs/ext4/xattr.c:2380
> ext4_xattr_set+0x13a/0x340 fs/ext4/xattr.c:2493
>
> This should be impossible since transaction start sets PF_MEMALLOC_NOFS.
> Add some assertions to the code to catch if something isn't working as
> expected early.
>
> Link: https://lore.kernel.org/linux-ext4/000000000000563a0205bafb7970@google.com/
> Signed-off-by: Jan Kara <jack@suse.cz>
Thanks, applied.
- Ted
prev parent reply other threads:[~2021-03-05 14:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 17:16 [PATCH] ext4: Add checks to xattr code that we have appropriate reclaim context Jan Kara
2021-03-05 14:29 ` Theodore Ts'o [this message]
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