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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250723072350.1742071-1-liuqiye2025@163.com> <202507230031.52B5C2B53@keescook> <119c3422-0bb1-4806-b81c-ccf1c7aeba4d@redhat.com> <8dd1e8f6-f96d-4d36-ac2a-c258ac842f75@redhat.com> <5cdd3e44-3e3c-4697-905a-ecc61093f7bc@163.com> Content-Language: en-US In-Reply-To: <5cdd3e44-3e3c-4697-905a-ecc61093f7bc@163.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wBH737sp4BouccnGw--.323S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7Zr18Xr1xWr4fAF17uw45Wrg_yoW8tF1kpF 1rKan0gr4kJryftrn2v3W0yr15trZ7G3y5W3s5W347Gr90qFy8Xr4xKF4UCFyjkr9Yka9F vr4jgF9ruFZ0vaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jodgAUUUUU= X-Originating-IP: [223.70.160.239] X-CM-SenderInfo: 5olx1xd1hsijqv6rljoofrz/1tbibhOTUGiAnoznpgAAsF X-Stat-Signature: mpuf1zh8gjdwkqiroekdc33o3csyerp1 X-Rspam-User: X-Rspamd-Queue-Id: 29CC9C000E X-Rspamd-Server: rspam02 X-HE-Tag: 1753262115-841692 X-HE-Meta: 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 Ux+fI6j5 tydAJOkxJUXytd3lsCfbDkxNWu37Yq6jwRvs2rGZXrJCnUBuHwg1dQ04bL2kfLXnmV/rTWf61eQciAPZcFvMeyFxgjCUkNF17/glJv6nFg6uo0OOFyDfjoOrBlneo9hIzsxWVFIw62+KZkOO7Hjj98DjSZNSX74kA/sdLyHcNaCZPBRMQZ9VyowSprYb/GAZQeYqsYrQIIs9hdWe5hnGMSvvek9bR3pCmpD5WwZfusNV6XcAJrSaLlL+eQJxNKahgbwc5KaIxOa6lrsjCBHv/t+g/8A0ekaEmv7bvMQh3IDlFOvNEj5Lvjp5/9Nfo10gRD98x0IMfdPWZQvXdbJ3J1FwNOpxp70WjEebtaK01NAbar+Vfhk+xshXRafOqCZg+qG1Le+fAtZEuurwjULHPLwC43CkXOwGI2vIoKRtrMTaizHePpVWBDrJaYTLDqYip9Wf4a+Ilc9mF9YJEbvAlqVHisplWt7UT9N0+r24Syp7qlJQn0zmsBa9ExA== 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: 在 2025/7/23 17:10, Xuanye Liu 写道: > 在 2025/7/23 16:42, David Hildenbrand 写道: >> On 23.07.25 10:05, David Hildenbrand wrote: >>> On 23.07.25 09:45, Xuanye Liu wrote: >>>> 在 2025/7/23 15:31, Kees Cook 写道: >>>>> On Wed, Jul 23, 2025 at 03:23:49PM +0800, Xuanye Liu wrote: >>>>>> The check_mm() function verifies the correctness of rss counters in >>>>>> struct mm_struct. Currently, it only prints an alert when a bad >>>>>> rss-counter state is detected, but lacks sufficient context for >>>>>> debugging. >>>>>> >>>>>> This patch adds a dump_stack() call to provide a stack trace when >>>>>> the rss-counter state is invalid. This helps developers identify >>>>>> where the corrupted mm_struct is being checked and trace the >>>>>> underlying cause of the inconsistency. >>>>> Why not just convert the pr_alert to a WARN? >>>> Good idea! I'll gather more feedback from others and then update to v2. >>> Makes sense to me. >> After discussion this with Lorenzo off-list, isn't the stack completely misleading/useless in that case? >> >> Whatever caused the RSS counter mismatch (e.g., unmapped the wrong pages, missed to unmap pages) quite possibly happened in different context, way way earlier. >> >> Why would you think the stack trace would be of any value when destroying an MM (__mmdrop)? >> >> Having that said, I really hate these "pr_*("BUG: ...") with passion. Probably we'd want to invoke the panic_on_warn machinery, because something unexpected happened. >> > The stack trace dumped here may indeed not reflect the root cause —— > the actual error could have occurred much earlier, for example during a > failed or missing page map/unmap operation. > The current stack (e.g., in __mmdrop() or exit_mmap()) is merely part > of the cleanup phase. Dumping the stack still has some chance of helping identify the issue — at the very least, it shows which task triggered the check.                                                        > > Given that, how should we go about identifying the root cause when such an issue occurs? > > Is there any existing way to trace it more effectively, or could we introduce a new mechanism > to monitor and detect these inconsistencies earlier?                                          > > Let’s brainstorm possible solutions together. > -- Thanks, Xuanye