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Mon, 23 Feb 2026 11:46:58 -0800 (PST) Date: Mon, 23 Feb 2026 19:46:55 +0000 From: Chris Bainbridge To: "Vlastimil Babka (SUSE)" Cc: Harry Yoo , Vlastimil Babka , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Hao Li , linux-mm@kvack.org Subject: Re: [PATCH] mm/slab: pass __GFP_NOWARN to refill_sheaf() if fallback is available Message-ID: References: <20260223133322.16705-1-harry.yoo@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam09 X-Stat-Signature: bfsakqoe6ybxixx3y5kzrugpdqxnkebc X-Rspamd-Queue-Id: 7CB0E40012 X-Rspam-User: X-HE-Tag: 1771876020-7661 X-HE-Meta: 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 m/Rg5wYI 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 > > 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 > > 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.