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[109.81.29.60]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4815a5af19fsm4618737f8f.24.2026.08.13.01.43.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Aug 2026 01:43:55 -0700 (PDT) Date: Thu, 13 Aug 2026 10:43:54 +0200 From: Michal Hocko To: Ye Liu Cc: Andrew Morton , Ye Liu , David Rientjes , Shakeel Butt , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/oom_kill: fix stale comment in constrained_alloc() Message-ID: References: <20260813030654.320269-1-ye.liu@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260813030654.320269-1-ye.liu@linux.dev> X-Stat-Signature: phywiqo46gjwft6sa5i1tsiagzsmoz99 X-Rspamd-Queue-Id: D9447C0002 X-Rspamd-Server: rspam03 X-Rspam-User: X-HE-Tag: 1786610637-104575 X-HE-Meta: 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 oULXvNHA O5f7Pvcj9zw2usKbs7KWIgqPPxmqLaABydYh+kI9Du/nriZPFun82QTXcodQqoGZQbdZcQUQIdseHy+AATL4Lu/iHbTAAweopbFsEm+kHLzByVNiRjfe4T8BjmUEud+GSAxNvkxwiE+Xwjng7iJ41GurbyXJu1H42Z7qj1LNPqi7m3zX18edzm04igHPXwnCBHhwxwxgw8yZ3H+h5HppoLRZcjLbLY7c4aELGOEmTYYspZIWZytKz/taLS8mu+8m6h+kRHhML9ePOuWDLjLfsfm5LAXPecywj1UJxz49GePgNTunP1PI4C7TR3alR6CHkZd2wIb6XMyCquZ07H5I8ws9srs9oU/rAHNm0jLWUzpMQGwlg8Cm0xuxNcM90i1JsUYCIs88EuK76hZB1rICtglQq9Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu 13-08-26 11:06:54, Ye Liu wrote: > From: Ye Liu > > The comment above the __GFP_THISNODE check in constrained_alloc() > is stale and inaccurate: it references __GFP_NOFAIL (which is not > checked here), claims the OOM killer does "random task kill" (it > uses badness scores), and mentions CONSTRAINT_THISNODE (which was > never added to the enum). Replace it with a description that > matches the actual code behavior. The comment is indeed confusing and stale. Your update unfortunatelly as well. This code is simply unreachable because we never trigger global OOM with __GFP_THISNODE (see __alloc_pages_may_oom) and for memcg OOM __GFP_THISNODE is immaterial. > Signed-off-by: Ye Liu > --- > mm/oom_kill.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 5f372f6e26fa..4b5c70aaece4 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -268,9 +268,9 @@ static enum oom_constraint constrained_alloc(struct oom_control *oc) > if (!oc->zonelist) > return CONSTRAINT_NONE; > /* > - * Reach here only when __GFP_NOFAIL is used. So, we should avoid > - * to kill current.We have to random task kill in this case. > - * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now. > + * __GFP_THISNODE means the allocation is restricted to a single node. > + * There is no dedicated constraint type for this case, so return > + * CONSTRAINT_NONE and let the normal OOM handling proceed. > */ > if (oc->gfp_mask & __GFP_THISNODE) > return CONSTRAINT_NONE; > -- > 2.25.1 -- Michal Hocko SUSE Labs