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b=jzG2Zj/e+EIoPw+tfCjb2lfy5xRRoLIUrpA7NYkJKV9AQsw/dmjQbyUhxk0emFDGm d5ZkyJHIuTuWRJp9sil5OpG6X2RNotWdQ0XnbWr8+Hj/w2H+sGSRgXM9Ec5NFlIps9 dRuK4XFh9hY0wAzSjyVbPtHCEv1T0eDzyzAjUq9M= Date: Fri, 12 Apr 2024 16:21:11 -0700 From: Andrew Morton To: Miaohe Lin Cc: Sidhartha Kumar , , , , Subject: Re: [PATCH v2] mm/memory-failure: fix deadlock when hugetlb_optimize_vmemmap is enabled Message-Id: <20240412162111.10f67ad0f001734464b53ad8@linux-foundation.org> In-Reply-To: <8d186776-f3b1-5d9a-2f94-fa249dee7d5f@huawei.com> References: <20240412025754.1897615-1-linmiaohe@huawei.com> <48647e5b-d15b-457b-9879-fb1b6bbaee27@oracle.com> <8d186776-f3b1-5d9a-2f94-fa249dee7d5f@huawei.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 46D3EA0011 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: u5uruuxui3tggc5mf6q1sgqkke9nk4yu X-HE-Tag: 1712964076-304121 X-HE-Meta: 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 kqYLnjAf fID5d0o4L96FyjgN9RmSaBJg8F8zMv9NoLk2WwGVcMUcdOeHdAmMF76V79RAy3wNr8xdWw48vTrbtDdT4lcJ/7OCi3S0PjRVTIVSo7uGxN5EQ5a1DWp/6wLMYdnjYScB7QArZWouehPoRsa6nH3zDz3bkQvRIuPO+FsZe8ejvJw5r+uWn2iIsyuCn7sFUOmqkmpMC2NdgbcDzNDaHlq+D8Yy0ZUAI4iCMSZ3XIE4s+I/B+pHR4vdR0SgRFsmNbvAwU9q91KRUwgEYTUuCZTOD4eGYwBNALzZfz1vEHGrOPNjxI+U= 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 Fri, 12 Apr 2024 16:11:52 +0800 Miaohe Lin wrote: > > I recently sent a patch[1] to convert dissolve_free_huge_page() to folios which changes the function name and the name referenced in the comment so this will conflict with my patch. It's in mm-unstable now, would you be able to rebase to that in a new version? > > This patch is a hotfixes, cc:stable one so the mm-unstable material will be based on top of this change. I've queued this change up as a -fix against v1. And I've retained this changelog addition: : This issue won't occur until commit a6b40850c442 ("mm: hugetlb: replace : hugetlb_free_vmemmap_enabled with a static_key"). As it introduced : rlock(cpu_hotplug_lock) in dissolve_free_huge_page() code path while : lock(pcp_batch_high_lock) is already in the __page_handle_poison(). And I've queued another -fix to reflow that block comment to 80 columns. --- a/mm/memory-failure.c~mm-memory-failure-fix-deadlock-when-hugetlb_optimize_vmemmap-is-enabled-v2-fix +++ a/mm/memory-failure.c @@ -155,14 +155,16 @@ static int __page_handle_poison(struct p int ret; /* - * zone_pcp_disable() can't be used here. It will hold pcp_batch_high_lock and - * dissolve_free_huge_page() might hold cpu_hotplug_lock via static_key_slow_dec() - * when hugetlb vmemmap optimization is enabled. This will break current lock - * dependency chain and leads to deadlock. - * Disabling pcp before dissolving the page was a deterministic approach because - * we made sure that those pages cannot end up in any PCP list. Draining PCP lists - * expels those pages to the buddy system, but nothing guarantees that those pages - * do not get back to a PCP queue if we need to refill those. + * zone_pcp_disable() can't be used here. It will + * hold pcp_batch_high_lock and dissolve_free_huge_page() might hold + * cpu_hotplug_lock via static_key_slow_dec() when hugetlb vmemmap + * optimization is enabled. This will break current lock dependency + * chain and leads to deadlock. + * Disabling pcp before dissolving the page was a deterministic + * approach because we made sure that those pages cannot end up in any + * PCP list. Draining PCP lists expels those pages to the buddy system, + * but nothing guarantees that those pages do not get back to a PCP + * queue if we need to refill those. */ ret = dissolve_free_huge_page(page); if (!ret) { _