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[109.81.82.69]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-39c3020da49sm2517510f8f.80.2025.04.03.12.49.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Apr 2025 12:49:51 -0700 (PDT) Date: Thu, 3 Apr 2025 21:49:50 +0200 From: Michal Hocko To: Kees Cook Cc: Shakeel Butt , Dave Chinner , Yafang Shao , Harry Yoo , joel.granados@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Josef Bacik , linux-mm@kvack.org, Vlastimil Babka Subject: Re: [PATCH] mm: kvmalloc: make kmalloc fast path real fast path Message-ID: References: <20250401073046.51121-1-laoar.shao@gmail.com> <3315D21B-0772-4312-BCFB-402F408B0EF6@kernel.org> <202504030920.EB65CCA2@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202504030920.EB65CCA2@keescook> X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 9454140009 X-Stat-Signature: 17frec35spbfkzwjn88ce1shaez8itz6 X-HE-Tag: 1743709793-430344 X-HE-Meta: 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 iCBu1Z1X s0pp3ojrv5YC53zHxU3H09vS1vuwa4Nfb+wX2CP5lWbiWEzU2Gt7+sSwW88aVnQFT1wSabqqsTOGr8O7ar4UZZ3S3P1M9ZzpLs5MzW6gDq2BP9jJiaxHcQxIlbkNRc0eF6fjj6N028VpuxD6ke+R1qaQXK7WMHNBnRtWhXpnhLx6nBM+TJm+n9XHQm8inmfB+uG2BU2upRYzqFrTBbNy0oIzt/afEq/Kxiv1vrfDaSrELEhqgP+/v0C9eMonBWxXMlKtg/e4gZdZ4RN34pSMbh3KABMKZx2t0GIpvTho0nKXuXJV0BRL8z6e06ZX940uKnLt/IdQs5t6ZZuMzC+ZupFI+ZWrY6T8Ad2s2Mj3L9KShW9R5Mt0lwilk70AKmdoxhMCc 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 Thu 03-04-25 09:21:50, Kees Cook wrote: > On Thu, Apr 03, 2025 at 09:43:39AM +0200, Michal Hocko wrote: [...] > > mm/slub.c | 8 +++++--- > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > diff --git a/mm/slub.c b/mm/slub.c > > index b46f87662e71..2da40c2f6478 100644 > > --- a/mm/slub.c > > +++ b/mm/slub.c > > @@ -4972,14 +4972,16 @@ static gfp_t kmalloc_gfp_adjust(gfp_t flags, size_t size) > > * We want to attempt a large physically contiguous block first because > > * it is less likely to fragment multiple larger blocks and therefore > > * contribute to a long term fragmentation less than vmalloc fallback. > > - * However make sure that larger requests are not too disruptive - no > > - * OOM killer and no allocation failure warnings as we have a fallback. > > + * However make sure that larger requests are not too disruptive - i.e. > > + * do not direct reclaim unless physically continuous memory is preferred > > + * (__GFP_RETRY_MAYFAIL mode). We still kick in kswapd/kcompactd to start > > + * working in the background but the allocation itself. > > I think a word is missing here? "...but do the allocation..." or > "...allocation itself happens" ? Thinking about this some more I would just cut this short and go with "We still kick in kswapd/kcompactd to start working in the background" Does that sound better? -- Michal Hocko SUSE Labs