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Tue, 24 Feb 2026 07:33:50 -0800 (PST) Date: Tue, 24 Feb 2026 15:33:48 +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> <5e767065-5536-4b95-8a42-c4be5d31c77f@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5e767065-5536-4b95-8a42-c4be5d31c77f@kernel.org> X-Stat-Signature: dob8nf6us86ad35tosp3nbu444ah5goj X-Rspam-User: X-Rspamd-Queue-Id: 72D66A0011 X-Rspamd-Server: rspam01 X-HE-Tag: 1771947232-157608 X-HE-Meta: U2FsdGVkX18GQJaYcSFjjika7cWQidq1thm42Nm6IG6a5xJCt4sPdIwLWmfDc9kbh1TxNqAwxNWoZGommCIrkgI+OV3hqXVBa9zOBqdzOJ8GaXz+erj8Hkc893Bh3vds/ONmJXCXoBiAD4yu5AGFxpsv6YURh9w0OnI31yN+15bKJcZtNGcMxWwj1WwmX7UQG8Otc9HgZeSUNIknOHy9zFCYDYB/Z8jeGMWnp1xiQPaipnszuTicW/K6Fr1IIcug29L6ZYk9CEF7rfol5fVzmnyM7W/JY8qSv18MUkXkUNtScbcUDkKik+IS9D9w+tLnAZ8ey9ZUVXpMFbWTDgcZY5GByQcp0I2yAKmRwGGSbaxB6SA0UtUGm5XqdiryTt5COBUo/+t/9VSS9YlT4zG2KhbBDxE11QEA1l0Hncm9iVn7jNbdznCng/ZgD21u2pEK8ef04bu8kAnygDnl6hIy74bn1ehXFyXmjRiloDw5TU1ZJaHKTUGoT0zM5VDsq2SPKKQF/INtNioZpgAI1eCAfnR6hhFIwh+jCuCqKT11EZaKvXIO/e1WME6iibRjgTdmQ4lWMS7KOOTg282K66s2URZrLp8AQZeRSDeeRyc8ehfwOKnUXk0mafzna49Th2WRXhe59FDI/3WqUb+awjFHZ/oDu7Ao2bnqwB2u5Z9BtHBPUsZUygPC6Y9akmc2UXxN+KQp+XQZp38qYu5nbXBBj2jDKojPYlL7hL3iqHxR99YrJdwphoIdEmRIF9di8S2hRYTvf7wQiSJaHtonOvAHkqCa1/foZiPWWiSBqAYjdEYGjso3lKQkfxPEpmrVd8r+1BVWVvO8G2HD/bKnnKPMAFPPiCwAjb1F1qyH57sYAB52qgA9neWv5WdVYCCJ3SzxEIL8YHB8ZkRlJATd1b/UVXeKUe7pP/uAEdBHGL4H6+bcSGmXbtCwhyVDK4xB7vqJ2WFF3ULbLLo0X9Q5ULV scSPg8XO 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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 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 > >> > 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. > > Great, can we add your Tested-by: then? > Thanks! Sure. Reported-and-tested-by: Chris Bainbridge