linux-kernel - Re: [Kernel Bug] WARNING in mempool_alloc

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Message-ID: <aYIh1wPm7BrId9dk@infradead.org>
Date: Tue, 3 Feb 2026 08:27:03 -0800
From: Christoph Hellwig <hch@...radead.org>
To: Harry Yoo <harry.yoo@...cle.com>
Cc: Vernon Yang <vernon2gm@...il.com>,
	李龙兴 <coregee2000@...il.com>,
	syzkaller@...glegroups.com, vbabka@...e.cz,
	akpm@...ux-foundation.org, cl@...two.org, rientjes@...gle.com,
	roman.gushchin@...ux.dev, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [Kernel Bug] WARNING in mempool_alloc_noprof

On Tue, Feb 03, 2026 at 06:52:39PM +0900, Harry Yoo wrote:
> Maybe the changelog could be rephrased a bit,
> but overall LGTM, thanks!

No, that does not make sense.  If mempool is used with __GFP_RECLAIM in
the flags it won't fail, and if it isn't, GFP_NOFAIL can't work.

So if there is any work in mempool_alloc it's that it should warn about
GFP_NOFAIL.  The fix is in the callers to not pass the flag, assuming
current kernels still do this.