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[109.81.82.69]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-43ec342babfsm9992235e9.1.2025.04.03.00.22.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Apr 2025 00:22:45 -0700 (PDT) Date: Thu, 3 Apr 2025 09:22:43 +0200 From: Michal Hocko To: Shakeel Butt Cc: Dave Chinner , Yafang Shao , Harry Yoo , Kees Cook , 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] proc: Avoid costly high-order page allocations when reading proc files Message-ID: References: <20250401073046.51121-1-laoar.shao@gmail.com> <3315D21B-0772-4312-BCFB-402F408B0EF6@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed 02-04-25 21:37:40, Shakeel Butt wrote: > On Wed, Apr 02, 2025 at 02:24:45PM +0200, Michal Hocko wrote: > > diff --git a/mm/util.c b/mm/util.c > > index 60aa40f612b8..8386f6976d7d 100644 > > --- a/mm/util.c > > +++ b/mm/util.c > > @@ -601,14 +601,18 @@ 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. > > */ > > if (size > PAGE_SIZE) { > > flags |= __GFP_NOWARN; > > > > if (!(flags & __GFP_RETRY_MAYFAIL)) > > flags |= __GFP_NORETRY; > > + else > > + flags &= ~__GFP_DIRECT_RECLAIM; > > I think you wanted the following instead: > > if (!(flags & __GFP_RETRY_MAYFAIL)) > flags &= ~__GFP_DIRECT_RECLAIM; You are absolutely right. Not sure what I was thinking... I will send a full patch with a changelog to wrap the situation up. -- Michal Hocko SUSE Labs