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Wed, 14 Jan 2026 15:38:04 +0000 From: Chris Mason To: Jane Chu CC: Chris Mason , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v4 1/2] mm/memory-failure: fix missing ->mf_stats count in hugetlb poison Date: Wed, 14 Jan 2026 07:37:47 -0800 Message-ID: <20260114153749.3004663-1-clm@meta.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260113080751.2173497-1-jane.chu@oracle.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [2620:10d:c0a8:1b::8e35] X-Proofpoint-ORIG-GUID: 0eQgpU3jhXliYXyCog7oiydOA_WFBhGB X-Authority-Analysis: v=2.4 cv=QKplhwLL c=1 sm=1 tr=0 ts=6967b881 cx=c_pps a=MfjaFnPeirRr97d5FC5oHw==:117 a=MfjaFnPeirRr97d5FC5oHw==:17 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=yPCof4ZbAAAA:8 a=TZCTYgXrSeyIqYBwcG0A:9 X-Proofpoint-GUID: 0eQgpU3jhXliYXyCog7oiydOA_WFBhGB X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTE0MDEzMSBTYWx0ZWRfXwribbCof2dL+ wsCpW9qYgWRbKngq9oNe1iNWe9pEa+q7VC1ZstItuI7wUB3PeWdiZEskNkHFWm0LyKlFrvFtUt3 0W8V/QmrFUjLq0C2ymCa9xcH0dI/QVS9QLVCW8Fsf4uX5FBDRYZIVG0I1fg/GQRsCOm3RonKtqq vm060xEGZs3F8wMSbJrisrwWPGn5SWG8i9mSEQb/cgjE5aUyqJy/kaYr/ePWA7P+qX7m1zr7otd msQ0vq/25VMXTn3KSKGtnByMGayThaXUySPA0Npeyrm1MWz9b7ThWEbTkUH9xjBj371HczlufFJ g8mk1H0zWk6F9n0iXczj7vZqfxsDsvZMW4hCDi2Pn30dmg3jQyMHY+lQGQDUkNCoMf+Y//VKItb AoCIgdENAkfJDIiH8E3ucH84eHQ6HnPPMNwWSxbozAVLaleBWZWLccW7gbNQfTBnPjx3A5exEpe fHWkduDXAdWDpLdABtA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2026-01-14_04,2026-01-14_01,2025-10-01_01 X-Stat-Signature: qa9hiwi968ra6q8s85sxead1apx3k7bx X-Rspam-User: X-Rspamd-Queue-Id: 25B5BA0018 X-Rspamd-Server: rspam08 X-HE-Tag: 1768405142-897813 X-HE-Meta: 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 vzwn/CXE g743xVas+p9x0kxXz/AZIdydry1WlKJygi/IXfHnob0jiaIM1pxBHwmrlQFTpkYVucndeY1kbBGmmCyueWcfjgXWHNGLlRt9orIAw0wUgFu6OETMynI5tCYZMV3Tgt9dZhE5h/2MGaIdkJprgwEMQhzxqGApjjSQPdhJ/U+3IWJmNWuGurVBBnW7y7gjgZT/KeO2zlRb311SduxfG7LJVGfoQV8mz4T8d75iZO6PQocObjN1sn+ej1z7Ren0TswQWUviZ71/y+nydI4Xe8BETgha3aZgtK7LoIPFlxUu6n7G3q42gpiG/Ht0bsJ9wuHAVmXMNM6ky4lFjlQYyqVk0VWxux/9H4YVwaQI2LJJMh7EA1Fmxi4tgPRCM3vkQNYXxH/tk/V+F7beRczFK5uY6AReg5kn6FULS6qDXaAvld96P4HRJoy0JyG/Zf3wyeWjiFT/r 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 Tue, 13 Jan 2026 01:07:50 -0700 Jane Chu wrote: > When a newly poisoned subpage ends up in an already poisoned hugetlb > folio, 'num_poisoned_pages' is incremented, but the per node ->mf_stats > is not. Fix the inconsistency by designating action_result() to update > them both. > > While at it, define __get_huge_page_for_hwpoison() return values in terms > of symbol names for better readibility. Also rename > folio_set_hugetlb_hwpoison() to hugetlb_update_hwpoison() since the > function does more than the conventional bit setting and the fact > three possible return values are expected. > Hi everyone, I ran mm-new through the AI patch review prompts, and this commit was flagged. The review below looks right to me: > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c [ ... ] > @@ -2029,22 +2037,29 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb) > *hugetlb = 1; > retry: > res = get_huge_page_for_hwpoison(pfn, flags, &migratable_cleared); > - if (res == 2) { /* fallback to normal page handling */ > + switch (res) { > + case -EINVAL: /* fallback to normal page handling */ > *hugetlb = 0; > return 0; > - } else if (res == -EHWPOISON) { > - if (flags & MF_ACTION_REQUIRED) { > - folio = page_folio(p); > - res = kill_accessing_process(current, folio_pfn(folio), flags); > - } > - action_result(pfn, MF_MSG_ALREADY_POISONED, MF_FAILED); > - return res; > - } else if (res == -EBUSY) { > + case -EBUSY: > if (!(flags & MF_NO_RETRY)) { > flags |= MF_NO_RETRY; > goto retry; > } > return action_result(pfn, MF_MSG_GET_HWPOISON, MF_IGNORED); > + case MF_HUGETLB_FOLIO_PRE_POISONED: > + case MF_HUGETLB_PAGE_PRE_POISON: > + if (flags & MF_ACTION_REQUIRED) { > + folio = page_folio(p); > + res = kill_accessing_process(current, folio_pfn(folio), flags); > + } > + if (res == MF_HUGETLB_FOLIO_PRE_POISONED) When MF_ACTION_REQUIRED is set, kill_accessing_process() overwrites res before this check. kill_accessing_process() returns either 0 or -EHWPOISON, so the check for MF_HUGETLB_FOLIO_PRE_POISONED (which is 3) will always be false in that path. This means action_result() will be called with MF_MSG_HUGE instead of MF_MSG_ALREADY_POISONED. Looking at action_result(): if (type != MF_MSG_ALREADY_POISONED && type != MF_MSG_PFN_MAP) { num_poisoned_pages_inc(pfn); update_per_node_mf_stats(pfn, result); } Does this cause incorrect counter increments for already-poisoned pages when MF_ACTION_REQUIRED is set? The original code called action_result() unconditionally with MF_MSG_ALREADY_POISONED regardless of whether kill_accessing_process() was called. Should a separate variable preserve the original res value before the call to kill_accessing_process()? > + action_result(pfn, MF_MSG_ALREADY_POISONED, MF_FAILED); > + else > + action_result(pfn, MF_MSG_HUGE, MF_FAILED); > + return res;