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bh=MuZcYPh1omkK8HEZAXjbGNcKNlLfSUT4dmGoKmWIVI4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ox99Oq+E1x0aCR9QfZaBIpMRK10/Kaz+mG8KeuckNkgLWjCTRzhtUq9JVB0EC7Kk4 GyF6+w9CgAafQfKNTcgK+OP8NtRg9l+qZXkBt2D6yc2VcjVIY2v2tPr3FvBO7hZ+u9 HOw9PmMgwLbMYu2z5RcvdsT/8Q/SeNDZA8eNY9EC3VrtEtjnrn+VC1Yd6iGZlxDZW0 dkcwA/ZsTTylD0Mw6FVLZYdzk5AdR37rXI8Ztz/474zp65yfHdeSBoT7iPhimRqcL+ KpFijJmccHuhawmLpX4haPNle7le9+KNYH8p/p3WO10Ba3uBmEmtMOHTHyJYRb4YcB QBSh6NQgvMcvQ== From: SJ Park To: SJ Park Cc: Andrew Morton , stable@vger.kernel.org, Baolin Wang , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/damon/vaddr: avoid hw-driven pte updates during damon_hugetlb_mkold() Date: Mon, 7 Sep 2026 11:08:20 -0700 Message-ID: <20260907180821.102875-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260907170358.100168-1-sj@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: E542AC000B X-Stat-Signature: mfrhjakkyfzzr7howt1t7p4a88mmo3ux X-HE-Tag: 1788804510-150541 X-HE-Meta: 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 8jWmkQbF r1x2OCRKsux/r2gysHNk0YL/oknGe/2+89F2Kpmfva2hFHFuOYpTTyM9qxaS7VzK8nElF7x7SY+T0tdR5YlwRdokh9L2nfLHgLNZmL+YTyWDYHwS4HgbF7dOSSN22TQqDkY3Rc+I+ooENFhD6FCSqKFKUlVPsvck/SzIT/iXiL3NsKjrRl7lnBg3hjv0Rw+EGNT6av++NAwRtzScq7EYPHpY5/54kEhmFyUSh3k9eXvyjRx9E++PzDQmtfRqC7cMRe8fezV+QfcJYehUOtCLNu4u1Mg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 7 Sep 2026 10:03:56 -0700 SJ Park wrote: [...] > +static bool damon_hugetlb_ptep_mkold(pte_t *pte, struct mm_struct *mm, > + struct vm_area_struct *vma, unsigned long addr, pte_t *entry) > +{ > + unsigned long psize = huge_page_size(hstate_vma(vma)); > + > + if (!pte_young(*entry)) > + return false; > + *entry = huge_ptep_get_and_clear(mm, addr, pte, psize); > + *entry = pte_mkold(*entry); > + set_huge_pte_at(mm, addr, pte, *entry, psize); > + return true; Sashiko says [1] this might violate BBM. But this is only for accessed bit change. So I don't think BBM is required here. Also, we intentionally do not flush TLB because this is just a best-effort monitoring. Please correct me if I'm wrong. [1] https://lore.kernel.org/20260907171613.A09B11F00A3A@smtp.kernel.org Thanks, SJ [...]