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From: Chris Bainbridge <chris.bainbridge@gmail.com>
To: "Vlastimil Babka (SUSE)" <vbabka@kernel.org>
Cc: Harry Yoo <harry.yoo@oracle.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Andrew Morton <akpm@linux-foundation.org>,
	Christoph Lameter <cl@gentwo.org>,
	David Rientjes <rientjes@google.com>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Hao Li <hao.li@linux.dev>,
	linux-mm@kvack.org
Subject: Re: [PATCH] mm/slab: pass __GFP_NOWARN to refill_sheaf() if fallback is available
Date: Tue, 24 Feb 2026 15:33:48 +0000	[thread overview]
Message-ID: <aZ3E3P2-Rmwt7YBT@debian.local> (raw)
In-Reply-To: <5e767065-5536-4b95-8a42-c4be5d31c77f@kernel.org>

On Tue, Feb 24, 2026 at 12:30:11PM +0100, Vlastimil Babka (SUSE) wrote:
> On 2/23/26 20:46, Chris Bainbridge wrote:
> > On Mon, Feb 23, 2026 at 05:48:25PM +0100, Vlastimil Babka (SUSE) wrote:
> >> On 2/23/26 14:33, Harry Yoo wrote:
> >> > When refill_sheaf() is called, failing to refill the sheaf doesn't
> >> > necessarily mean the allocation will fail because a fallback path
> >> > might be available and serve the allocation request.
> >> > 
> >> > Suppress spurious warnings by passing __GFP_NOWARN along with
> >> > __GFP_NOMEMALLOC whenever a fallback path is available.
> >> > 
> >> > When the caller is alloc_full_sheaf() or __pcs_replace_empty_main(),
> >> > the kernel always falls back to the slowpath (__slab_alloc_node()).
> >> > For __prefill_sheaf_pfmemalloc(), the fallback path is available
> >> > only when gfp_pfmemalloc_allowed() returns true.
> >> > 
> >> > Reported-by: Chris Bainbridge <chris.bainbridge@gmail.com>
> >> > Closes: https://lore.kernel.org/linux-mm/aZt2-oS9lkmwT7Ch@debian.local
> >> > Fixes: 1ce20c28eafd ("slab: handle pfmemalloc slabs properly with sheaves")
> >> > Link: https://lore.kernel.org/linux-mm/aZwSreGj9-HHdD-j@hyeyoo
> >> > Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
> >> 
> >> Thanks, added to slab/for-next-fixes.
> >> Hopefully Chris can confirm it works (without adding the __NOWARN to btrfs code)
> > 
> > Yes, it works for my test case.
> 
> Great, can we add your Tested-by:  then?
> Thanks!

Sure.

Reported-and-tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>


      reply	other threads:[~2026-02-24 15:33 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-23 13:33 Harry Yoo
2026-02-23 16:48 ` Vlastimil Babka (SUSE)
2026-02-23 19:46   ` Chris Bainbridge
2026-02-24 11:30     ` Vlastimil Babka (SUSE)
2026-02-24 15:33       ` Chris Bainbridge [this message]

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