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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-9087ff9d814sm8251026d6.10.2026.08.04.12.15.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Aug 2026 12:15:38 -0700 (PDT) Date: Tue, 4 Aug 2026 15:15:37 -0400 From: Gregory Price To: "Matthew Wilcox (Oracle)" Cc: Andrew Morton , Jane Chu , linux-mm@kvack.org, Muchun Song , Oscar Salvador , David Hildenbrand , Miaohe Lin , Naoya Horiguchi , Jan Kara , linux-fsdevel@vger.kernel.org, Christian Brauner , Jiaqi Yan Subject: Re: [PATCH v8 10/15] mm: Check individual hugetlb pages for poison Message-ID: References: <20260731200802.574821-1-willy@infradead.org> <20260731200802.574821-11-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260731200802.574821-11-willy@infradead.org> X-Stat-Signature: osidhpu43n9dpwdi4d58wq5ri79t1gee X-Rspamd-Queue-Id: 2F1AA2000B X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1785870939-618278 X-HE-Meta: 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 F4pTGn/z PSCRDLPZsakVyPReYvawTY76eipT9ifPDjk6evS4nr6fLKauGd7FuxhsiPRCUC27SB1f1wEP/hDE6aGTYHu/Dvclb+NOV6XzB6+7KW902tODmjoFmRC9Bzb9sOj2ucL8SMKnsySLiG8xqVHThvi6Pv1OgF/Je1Qpqc4tMXAm/RWq4F8XwOddtAwIWSLG51P67wzJcQp3JeHAMg62q2yqDNpN0u9t9z/uxK0V1/wrv0xdOZ9qa/67Hzq9jZf5T7LfL+1U4PX7t6ZrzNQDRo7bdwQlOGKgBQ0mqSVsoVsh3nWEmyIVZINmLTbnxF62k9lUT/Uz6VSgJYNvTwwHfjaEzikvr4da4zZYA+h4QBOYf7fzdpURCtk8Vocz6IR1YjiT+fbHpYGkS93gkxGP1VEJHOocWwbo1bX3yxmP1dd4A3IUi25rW25rNpYK5aZgRf8PwoR1d699+CXhFowNR4yvGMzABZw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jul 31, 2026 at 09:07:55PM +0100, Matthew Wilcox (Oracle) wrote: > +/* > + * We have no reference on the folio containing this page. > + * The hugetlb_lock keeps hugetlb folios from being freed. > + */ > +bool hugetlb_unref_page_hwpoison(const struct page *page) > +{ > + const struct folio *folio; > + unsigned long flags; > + bool ret; > + > + spin_lock_irqsave(&hugetlb_lock, flags); > + folio = page_folio(page); > + if (!folio_test_huge_poison(folio)) { > + ret = PageHWPoison(page); > + goto unlock; > + } > + > + ret = precise_page_poisoned(folio, page); > +unlock: > + spin_unlock_irqrestore(&hugetlb_lock, flags); > + return ret; > +} > + I ended up with the same question as sashiko - i think this behavior implies we must hold a reference on the page, otherwise the folio can be invalid and all these accesses are unsafe. But that must be the existing behavior for poison checks like this, so this is at least no worse. Not sure it's worth addressing. Reviewed-by: Gregory Price (Meta)