Re: [PATCH] mm/slab: pass __GFP_NOWARN to refill_sheaf() if fallback is available

["Vlastimil Babka (SUSE)" <vbabka@kernel.org>]

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!