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a=rsa-sha256; c=relaxed/relaxed; d=stgolabs.net; s=dreamhost; t=1722723360; bh=qoRbMol++GV7pnk5stu7PzDGVi+tenflIWLybgOoYpQ=; h=Date:From:To:Cc:Subject:Content-Type; b=GpYabR1+JldGHYgLU8Fam2TUJW7/XqSXwlEXNK59ht97fYY5HwxMDh1e/PlvpFnTx rHz2ZtDYcwC+NoXhbOw5Klj25mqpcsm3B/UQikKPjr4X2TcTlSO3fOmLkFaKx2lYwI TFz5kfHvy2qo2kYIRL4jG6l2Cw3MO6vtVw8jS3YY6F5vq5dTj/2WqAuSLZt2YEWb1u y0cEY8RZeOb98a/hzA+ROzPurR7bdunFhjtYuQamdNxDn9wnsL/PlAbWnNhxVWExoa EK4dgtQvYr6tqFOqD7Q5lqPeNi0fmeTNLkO3ojtGegX72iGEfawZdCxXyEADIQM5VP PntjJJdH45gxA== Date: Sat, 3 Aug 2024 15:15:56 -0700 From: Davidlohr Bueso To: Michal Hocko Cc: Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org, 42.hyeyoo@gmail.com, cl@linux.com, hch@infradead.org, iamjoonsoo.kim@lge.com, lstoakes@gmail.com, penberg@kernel.org, rientjes@google.com, roman.gushchin@linux.dev, urezki@gmail.com, v-songbaohua@oppo.com, vbabka@suse.cz, virtualization@lists.linux.dev, hailong.liu@oppo.com, torvalds@linux-foundation.org Subject: Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL Message-ID: <3mevqjzu2emxd2f3zkrurnzcal67k4lpkcdqzfs75qhp4uflbn@skz6q5odetdr> Mail-Followup-To: Michal Hocko , Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org, 42.hyeyoo@gmail.com, cl@linux.com, hch@infradead.org, iamjoonsoo.kim@lge.com, lstoakes@gmail.com, penberg@kernel.org, rientjes@google.com, roman.gushchin@linux.dev, urezki@gmail.com, v-songbaohua@oppo.com, vbabka@suse.cz, virtualization@lists.linux.dev, hailong.liu@oppo.com, torvalds@linux-foundation.org References: <20240724085544.299090-1-21cnbao@gmail.com> <20240724085544.299090-6-21cnbao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20240425 X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 70C1B100005 X-Stat-Signature: gcp9snd8sxu7oksxmojzzc3tr5fsig5m X-HE-Tag: 1722723362-168670 X-HE-Meta: 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 rCRLIYuk KNQ7833vGpvoyQyIdciqGoCBFh5JCATQ/a8vg/LKQQ99/K47MraVM65OJdpBnQU+ZGuQ28B0ecY/naBvQ263LBvKIrMcjJ5pAE1v+2ucsg4K0OIgrLNBi08CzD0Efj842SMJ7t7zXqPocisi9ZO2pGkEDePKG3ptyuqDl0FrpC6tsNqat3+m+Omy1OYREULBEUPFOwI6Og2G/31kg6usKRPvdK1cPGPE8tQ2oasR/sRNBYLdwgnTWR3Mr6+IQF4/vQ0pLJrUMVRt7JeqfaO2mRlwy+7XvOWYlf+qQUuTS01W4n3A2r45HsnKD3Z45YsqIfw/9cDoQHVzRUZNo/Pd5zUQLDRIfNqf2LQf41LK0Mf8N3F7aSaGs8gQRgDlSP1fpNF6w 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, 29 Jul 2024, Michal Hocko wrote: >Because it is really hard to figure out what it is supposed to mean. >If the caller uses __GFP_NOFAIL then it is (should be) impossible and if >NOFAIL is not used then why does it need to check for > (gfp & ~__GFP_NOFAIL) != GFP_KERNEL? Agreed, this is pointless - and cannot recall why it was justified to have in the first place. But I think we should revert back to the original check then, which is there to distinguish failure cases between normal (GFP_KERNEL) and nested (GFP_ATOMIC) contexts. Removing the check altogether would change the fallback for regular allocations. So this would be: - if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) { + if (tbl == NULL && gfp != GFP_KERNEL) { Thanks, Davidlohr