linux-kernel - Re: [BUG] WARNING in bdev

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Message-ID: <aEdIsaZIcR_co42X@casper.infradead.org>
Date: Mon, 9 Jun 2025 21:48:49 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Jan Kara <jack@...e.cz>
Cc: Xianying Wang <wangxianying546@...il.com>, viro@...iv.linux.org.uk,
	brauner@...nel.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [BUG] WARNING in bdev_getblk

On Mon, Jun 09, 2025 at 03:54:01PM +0200, Jan Kara wrote:
> Hi!
> 
> On Mon 09-06-25 16:39:15, Xianying Wang wrote:
> > I encountered a kernel WARNING in the function bdev_getblk() when
> > fuzzing the Linux 6.12 kernel using Syzkaller. The crash occurs during
> > a block buffer allocation path, where __alloc_pages_noprof() fails
> > under memory pressure, and triggers a WARNING due to an internal
> > allocation failure.
> 
> Ah, this is a warning about GFP_NOFAIL allocation from direct reclaim:

It's the same discussion we had at LSFMM.  It seems like we have a lot
of "modified syzkaller" people trying this kind of thing.