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	Mon, 28 Sep 2026 05:28:52 +0000
Date: Sun, 27 Sep 2026 22:28:52 -0700
From: Christoph Hellwig <hch@infradead.org>
To: "Vlastimil Babka (SUSE)" <vbabka@kernel.org>
Cc: Hao Ge <hao.ge@linux.dev>, David Howells <dhowells@redhat.com>,
	Paulo Alcantara <pc@manguebit.org>, Harry Yoo <harry@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Hao Li <hao.li@linux.dev>, Christoph Lameter <cl@gentwo.org>,
	David Rientjes <rientjes@google.com>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	"Christian Brauner (Amutable)" <brauner@kernel.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Christoph Hellwig <hch@infradead.org>, netfs@lists.linux.dev,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, Erhard Furtner <erhard_f@mailbox.org>,
	stable@vger.kernel.org
Subject: Re: [PATCH v2] netfs: Fix missing alloc tagging of direct mempool
 allocations
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References: <20260923063759.34667-1-hao.ge@linux.dev>
 <0d798541-6486-44ff-ae57-f631d1465688@kernel.org>
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On Thu, Sep 24, 2026 at 11:36:19AM +0200, Vlastimil Babka (SUSE) wrote:
> > Closes: https://lore.kernel.org/all/0b004319-9ef7-437c-a4dd-174d6a9a83db@mailbox.org/
> > Tested-by: Erhard Furtner <erhard_f@mailbox.org>
> > Suggested-by: Suren Baghdasaryan <surenb@google.com>
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Hao Ge <hao.ge@linux.dev>
> 
> Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
> 
> Seems ok enough as a hotfix. The naming perhaps isn't ideal, we have
> mempool_alloc_preallocated() already for the opposite case. Maybe
> mempool_alloc_no_preallocated() to complement it? Rather long though.

None of this is ok.  Directly alling into mempool->alloc, using a
wrapper and not is stupid and broken.  Just switch the code to use
mempool_alloc undconditionally or to use a manually
kmalloc/kmem_cache_allow if the subsystem has a really good reason
to not use a mempool for non-writeback requests, but it'd better be
a really good and well-documented reason.