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Thu, 13 Aug 2026 09:50:25 +0000 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Thu, 13 Aug 2026 17:50:21 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/oom_kill: fix stale comment in constrained_alloc() To: Michal Hocko Cc: Andrew Morton , Ye Liu , David Rientjes , Shakeel Butt , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260813030654.320269-1-ye.liu@linux.dev> Content-Language: en-US From: Ye Liu In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: A443520009 X-Rspam-User: X-Stat-Signature: fgk37jd4y85arq6pi81pzci4wsxz7fkb X-Rspamd-Server: rspam06 X-HE-Tag: 1786614626-770681 X-HE-Meta: U2FsdGVkX19tHkF5Qa9gBSQ/x3ajVBpc99jFJt1dgKmaDGhNui/ewSZWjCURgeTieQ/ULwyfkX78VqEJKfKhaOZB8j7sL5F4i9Zi2loVu6AoyFMeiKzRqV2cIAhQsfey12XxvKn/Rg02PphQNO1zopdDnkm6A1ZDCwMHuNugmBzWfVUfBz1BSDPjIqK1yBQUfOkRBzuI1BRPAIdfskDgm9A1FbsKp1MvounKNf6kcfL9s7/n4pyZ1zb4F2J72REJcRBlTVytr7e58jwdPOss8YDLkkJ16P9b4AES22kU2Dhbn33w+AX0cREKgXhOYIU8h3PwaOCF0X30kpjZ1fSJYBhE7+41doGymH85djkW77cMg7bf8hMPfyxHEQZA77hDRUGD469PFptRcDOnWq+a6Df8uHdFpa6RYMNA3Ww2LchJY7BQywFrVZ7tmoWwbCfrN7uKW83CPkEu9h2euvT4kacB2uWOBMc+Fe4SnVT3I/jQiMSGqDDl6lRHn1YBLK3EUJJz38YxqCRLJu3OVWqNlmiEKdgjc+neBKk+2daF9zF4Z1hkWDw7BM7nL2Sy3N8PEA99cq3tEFew1KPPy/llxAQtpkFuWWbzTZLsBWN3Z00W//CAYRDAR/GHd4ge1FmcJa+sfDbCqP2bE8wtgYDWlbzyMUqogRgKmk5Trwt29n8huGzPj5GbbsVJrRgqdiG2mvnD/es9y4uYYzd6BRDTvfG8EAW3WYiMG2HylUvAqgp/vuBT+SCUxntLzQHt1xTc0D26kpaAk3sVSuimrMK6DuDoh70hyFCPx62wLFeUhZZkIh9RKQpKUXz97Uc9KEvwzRrIRjdBmEALNjL2kOFKbh8oMyNTl8xMhzHWAR8OKoqYG9zURvpulc1g78COFI3KoGm8PAXrtdx9awnRm6fKxXj2JFBKLRJMUEVqSJCsv5oUpMJYvdRUUgVhUyD/QwcaDlMZF5EUvXNdeRIDekd xm82bNm7 zSuT0Ttd1KPynYvt6FEkPSKvZJTJ/ZEdzMRThUqbUFkrGYr10ZkjzGC0J3m+BpT/Ns/2af7EBla4oY5lr0fAOZDlgYAE4buOd2bBZDMYtNPzqdcbuii9blgF4TgU9zxhZyrScVqAXOSM8G80uQwM71NQQ7VLWmP6IUjum71/XHHnqbVyTKshlruKWWxMx9hyUvwXhGpfzCTAb9Cfx8B1JuiRN5hhN9QpI1IgKRGcpUuOkUbqCH4FbbkxJrOQbChkZ4q/FjbUmAM6iJNBqkmI9MQEK5w0g5vn2MnQxnt4jALrx+rMmTXY0DjUdG575ADBk3hxIEcvu6bCt8L+MZMQ6gCCuIxDqRhKPF/gc Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 在 2026/8/13 16:43, Michal Hocko 写道: > 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. > I directly deleted the invalid code and sent v2. >> 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 > -- Thanks, Ye Liu