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[109.81.84.7]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483bd6854c7sm10875895e9.0.2026.02.24.06.34.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Feb 2026 06:34:20 -0800 (PST) Date: Tue, 24 Feb 2026 15:34:19 +0100 From: Michal Hocko To: Shakeel Butt Cc: Christoph Hellwig , Uladzislau Rezki , Mikulas Patocka , "Vishal Moola (Oracle)" , SeongJae Park , Andrew Morton , zkabelac@redhat.com, Matthew Sakai , linux-mm@kvack.org, dm-devel@lists.linux.dev Subject: Re: [PATCH] mm: allow __GFP_RETRY_MAYFAIL in vmalloc Message-ID: References: <32bd9bed-a939-69c4-696d-f7f9a5fe31d8@redhat.com> Precedence: bulk X-Mailing-List: dm-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue 24-02-26 06:22:15, Shakeel Butt wrote: > On Tue, Feb 24, 2026 at 06:03:13AM -0800, Christoph Hellwig wrote: > > On Tue, Feb 24, 2026 at 01:22:36PM +0100, Michal Hocko wrote: > > > One thing that we could do to improve __GFP_RETRY_MAYFAIL resp. > > > __GFP_NORETRY is to use NOWAIT allocation semantic for page table > > > allocations as those could be achieved by scoped allocation context. > > > This could cause pre-mature failure after the whole bunch of memory has > > > already been allocated for the backing pages but considering that page > > > table allocations should be more and more rare over system runtime it > > > might be just a reasonable workaround. WDYT? > > > > Why bother? __GFP_RETRY_MAYFAIL has pretty lose semantics. Trying > > too hard to allocate PTEs is not breaking the overall concept. > > > > One thing __GFP_RETRY_MAYFAIL is very clear about is to not trigger the > oom-killer which is not the case for GFP_KERNEL. There are users who explicitly > use __GFP_RETRY_MAYFAIL to avoid oom-killer. > > Mikulas, is that the reason you are using __GFP_RETRY_MAYFAIL in your use-case? yes https://lore.kernel.org/all/32bd9bed-a939-69c4-696d-f7f9a5fe31d8@redhat.com/T/#u -- Michal Hocko SUSE Labs