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Date: Mon, 23 Mar 2026 07:44:17 +0100
From: Christoph Hellwig <hch@lst.de>
To: Vasily Gorbik <gor@linux.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
	Chaitanya Kulkarni <kch@nvidia.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com,
	syzbot <syzbot+09ddb593eea76a158f42@syzkaller.appspotmail.com>
Subject: Re: [PATCH] block: fix bio_alloc_bioset slowpath GFP handling
Message-ID: <20260323064417.GA24833@lst.de>
References: <69bdcdcd.050a0220.3bf4de.002f.GAE@google.com> <p01.gc6e9ad5845ad.ttca29g@ub.hpns>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Sun, Mar 22, 2026 at 03:35:10AM +0100, Vasily Gorbik wrote:
> bio_alloc_bioset() first strips __GFP_DIRECT_RECLAIM from the optimistic
> fast allocation attempt with try_alloc_gfp(). If that fast path fails,
> the slowpath checks saved_gfp to decide whether blocking allocation is
> allowed, but then still calls mempool_alloc() with the stripped gfp mask.
> That can lead to a NULL bio pointer being passed into bio_init().
> 
> Fix the slowpath by using saved_gfp for the bio and bvec mempool
> allocations.

Looks good, thanks:

Reviewed-by: Christoph Hellwig <hch@lst.de>