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AJvYcCWaPeefHHT6WwxmyzOexcR37mK8Uc7MIEbr/N/AOfcSPFLVGrGFl9KUO2ba7LCccNIGzQXtMnOqQ+xPZQ3ZP2tzPLY= X-Gm-Message-State: AOJu0YxO0VOlWqEVnOE7zGyJPBJVgVdsVlyy92Q9msPcfZjsXi0kc5vL x7rm9NCc43IvCY/GvaCdHBSdi2cRH9WNBjzxA1w9qg1QiwxBg184df/bTIFnXVlBAW9yMSo224y 8lbl6rleTBOXGs5OwQaKGxpCXEiw= X-Google-Smtp-Source: AGHT+IHvqevpxTBqxe2U1oPZ9NK3XHWVM+8jFGqqUX+V26YK7M0Yarmgv2RAFjJglmmes1G8zWbJ9XITEyfN3of4NHY= X-Received: by 2002:a05:6102:3e18:b0:492:ad30:b6e8 with SMTP id ada2fe7eead31-492ad30ca36mr3884011137.3.1721690558425; Mon, 22 Jul 2024 16:22:38 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Barry Song <21cnbao@gmail.com> Date: Tue, 23 Jul 2024 11:22:26 +1200 Message-ID: Subject: Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL To: Christoph Hellwig Cc: Michal Hocko , akpm@linux-foundation.org, linux-mm@kvack.org, Barry Song , Uladzislau Rezki , Lorenzo Stoakes , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 743D440010 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: oqot6pked7cwcs615fwxzuxrmswxs8dq X-HE-Tag: 1721690559-215974 X-HE-Meta: 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 gmCQ2H7Q 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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, Jul 23, 2024 at 11:18=E2=80=AFAM Christoph Hellwig wrote: > > On Mon, Jul 22, 2024 at 11:01:23AM +0200, Michal Hocko wrote: > > __GFP_$FOO are usually low level. GFP_$FOO are high level and they > > combine several subflags to have a specific meaning. So this would need > > to be GFP_NOFAIL. Btw. the same applies to __GFP_NORETRY and > > __GFP_RETRY_MAYFAIL. > > True. But I think adding GFP_NOFAIL and slowly upping the enforcement > that no one is using __GFP_NOFAIL directly will get us a similar effect > to my *_nofail proposal. It will require manual or scripted checking > instead of relying on the compiler, but it's much better than what we > have right now. I agree. My proposal was actually to enforce blocking in GFP_NOFAIL while t= he post code was an ugly hack at the lower level with __GFP_NOFAIL.