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Thu, 16 May 2024 16:45:23 +0800 Subject: Re: [PATCH v2] mm/huge_memory: don't unpoison huge_zero_folio To: Oscar Salvador , David Hildenbrand CC: , , , , , References: <20240515023607.870022-1-linmiaohe@huawei.com> From: Miaohe Lin Message-ID: Date: Thu, 16 May 2024 16:45:22 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.173.135.154] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500002.china.huawei.com (7.192.104.244) X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 43D4720019 X-Stat-Signature: xynr3n9je99jwqnj8wuzahys3rauxaoe X-HE-Tag: 1715849127-446568 X-HE-Meta: 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 BwhVVNYh O8wspYwsTikDy/gJM3PL7XKCfATV4j3sXkMOgPp3ikNOMbbHgiD8PXARJHNQ2oP/5nJEtWyWV5X6Kdk3/zGNOqXhDAj5tqjTXALYxikdkVCYEjBXJFQ2DZS+A/ZqWwMXY0ZQKCHrCwGwHalkgsd79Z7RqlmE5XscwKgHpgOijnrKG8ilNbCadFZqzco0+oGcE/XhimMVglQoxHJWlTEO6SgBqxaESVeJ5K1gvEUlYJvcGys3Iw3LXpsBVqok9Bsp2VKdU 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 2024/5/16 16:26, Oscar Salvador wrote: > On Wed, May 15, 2024 at 05:55:39PM +0200, David Hildenbrand wrote: >>> + if (is_huge_zero_folio(folio)) { >>> + unpoison_pr_info("Unpoison: huge zero page is not supported %#lx\n", >>> + pfn, &unpoison_rs); >>> + goto unlock_mutex; >>> + } >>> + > > Sorry for spamming your reply David, but for some unknown reason I am not able > to find the original patch in my mailbox, in none of the two accountes I am > subscribed, so I guess I will have to reply here. > > Just two things > > 1) We do not care if someone grabs a refcount for huge_zero_folio, > because since it is not supported anyway the outcome will not change. > Also, AFAIK, there is no chance we can unpoison that folio. > Therefore, I would just lift the check two blocks and place it right after > the hw_memory_failure check. > > 2) The whole thing is unsupported, but you will return -EBUSY while you > should be returning -EOPNOTSUPP AFAICS. > Thanks for your comment. Do you mean something like below? diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 16ada4fb02b7..a9fe9eda593f 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -2546,6 +2546,13 @@ int unpoison_memory(unsigned long pfn) goto unlock_mutex; } + if (is_huge_zero_folio(folio)) { + unpoison_pr_info("Unpoison: huge zero page is not supported %#lx\n", + pfn, &unpoison_rs); + ret = -EOPNOTSUPP; + goto unlock_mutex; + } + if (!PageHWPoison(p)) { unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n", pfn, &unpoison_rs); Thanks. . > with that you can add: > > Reviewed-by: Oscar Salvador > > >