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[109.81.17.175]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4873069961esm186640855e9.12.2026.03.30.06.54.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Mar 2026 06:54:39 -0700 (PDT) Date: Mon, 30 Mar 2026 15:54:38 +0200 From: Michal Hocko To: David Rientjes Cc: Andrew Morton , Vlastimil Babka , Suren Baghdasaryan , Brendan Jackman , Johannes Weiner , Zi Yan , Petr Mladek , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [patch] mm, page_alloc: reintroduce page allocation stall warning Message-ID: References: <30945cc3-9c4d-94bb-e7e7-dde71483800c@google.com> <231154f8-a3c3-229a-31a7-f91ab8ec1773@google.com> 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: <231154f8-a3c3-229a-31a7-f91ab8ec1773@google.com> On Sun 29-03-26 18:08:52, David Rientjes wrote: > Previously, we had warnings when a single page allocation took longer > than reasonably expected. This was introduced in commit 63f53dea0c98 > ("mm: warn about allocations which stall for too long"). > > The warning was subsequently reverted in commit 400e22499dd9 ("mm: don't > warn about allocations which stall for too long") but for reasons > unrelated to the warning itself. I think it makes sense to summarize reasons for the revert. I would propose to change the above to somehting like " The warning was subsequently reverted in commit 400e22499dd9 ("mm: don't warn about allocations which stall for too long") because it was possible to generate memory pressure that would effectivelly stall further progress through printk execution. " > @@ -4841,6 +4884,9 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > if (current->flags & PF_MEMALLOC) > goto nopage; > > + /* If allocation has taken excessively long, warn about it */ > + check_alloc_stall_warn(gfp_mask, ac->nodemask, order, alloc_start_time); > + > /* Try direct reclaim and then allocating */ > if (!compact_first) { > page = __alloc_pages_direct_reclaim(gfp_mask, order, alloc_flags, Is there any specific reason for this placement? Compaction can take quite some time as well. -- Michal Hocko SUSE Labs