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s=arc-20220608; d=hostedemail.com; t=1660954109; a=rsa-sha256; cv=pass; b=8qFCLSyQIZIkbAnjoL/tJANJoNps/gSPZVrn8TfWBB4NyxDJ/UQZcBwRWvPXOE7hrcS8gL hEejhQveiuipMOeiejBbcC6xqnJPAD6IRUlk/2xpCIvpPLlHe0ATO9GIJ6MJhm/yVBS7Ei EDoBFs0RsMaO0ceXcoM2L+CqvDRw0EI= X-Stat-Signature: m4zxqijx3cjs1mqjants9ke34ui93ko8 X-Rspam-User: Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2022-7-12 header.b=k6R07Acm; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=UyJZ8qw9; arc=pass ("microsoft.com:s=arcselector9901:i=1"); spf=pass (imf29.hostedemail.com: domain of mike.kravetz@oracle.com designates 205.220.177.32 as permitted sender) smtp.mailfrom=mike.kravetz@oracle.com; dmarc=pass (policy=none) header.from=oracle.com X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 8BB431200F5 X-HE-Tag: 1660954109-841609 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: On 08/19/22 18:12, Baolin Wang wrote: > Hi, > > On ARM64 architecture, it can support CONT-PTE/PMD size hugetlb. When > looking up hugetlb page by follow_page(), we will hold the incorrect > pte/pmd lock for the CONT-PTE/PMD size hugetlb page, which will make > the pte/pmd entry unstable even under the lock and cause some potential > race issues. So considering the CONT-PTE/PMD size hugetlb, this patch set > changes to use the correct function to get the correct pte/pmd entry lock > to make the pte/pmd entry stable. Thank you for looking at this. I often get confused by arm64 CONT-PTE/PMD layout, so my understanding may be wrong. Can we use the PMD page lock for locking both CONT-PTE and CONT-PMD entries? Again, I may be confused by the CONT-* page table layout, but it seems these would all be referenced via that same PMD page of the page table. Or, perhaps CONT-PMD can span multiple PMD pages? If we can use PMD page for locking, this would be much finer grain that lock in the mm. -- Mike Kravetz