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[209.85.220.65]) by mx.google.com with SMTPS id m37sor2664059pla.6.2019.06.13.03.45.59 for (Google Transport Security); Thu, 13 Jun 2019 03:45:59 -0700 (PDT) Received-SPF: pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=OP0W8yRl; spf=pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=kernelfans@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=uCwWLrWN30s9tONuGry7ZPwH/e/7xLPMQjqyo7O5eBk=; b=OP0W8yRlUthFREqCxHMZcGfrR7ObjX7GSg3sDYQOctNsRHbm2Lqcb/opmbujosV95J Kh99aG4N5q3cD8Qe5BzWR9WJEMlx27hM+S6fiT/SGbKF6lFXXfH5hU2LKUg7g4jKajV7 i+CpumuA89UHiI+0KEwM0sEc8xCFxvGVPnOo/wSJ+eHrjcMmDLkXIKzRiOrMhUlW3xX2 0j2845eItLsOowqgOEDPMtCStDCTisuEjva0X94eD9UD6KLLzhjtMkuZ7kqhppDiaS4C nwXrzRFqbHigTy4SOi86TzPaELfID3cNgUHIFdnNBPTaW8jZPP1i+VQqes+JkhBDgzO0 JNAw== X-Google-Smtp-Source: APXvYqz9LfQKa/wrOUIWnFUFZ/wGYmdDsdGq/Xe0dgLwb9nKtqXnSonygBcQvBArP0L1tEzTp904NA== X-Received: by 2002:a17:902:a506:: with SMTP id s6mr12547789plq.87.1560422758789; Thu, 13 Jun 2019 03:45:58 -0700 (PDT) Received: from mylaptop.redhat.com ([2408:8207:7825:dd90:9051:d949:55f9:678b]) by smtp.gmail.com with ESMTPSA id a13sm2813285pgh.6.2019.06.13.03.45.50 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 13 Jun 2019 03:45:58 -0700 (PDT) From: Pingfan Liu To: linux-mm@kvack.org Cc: Pingfan Liu , Ira Weiny , Andrew Morton , Mike Rapoport , Dan Williams , Matthew Wilcox , John Hubbard , "Aneesh Kumar K.V" , Keith Busch , Christoph Hellwig , Shuah Khan , linux-kernel@vger.kernel.org Subject: [PATCHv4 2/3] mm/gup: fix omission of check on FOLL_LONGTERM in gup fast path Date: Thu, 13 Jun 2019 18:45:01 +0800 Message-Id: <1560422702-11403-3-git-send-email-kernelfans@gmail.com> X-Mailer: git-send-email 2.7.5 In-Reply-To: <1560422702-11403-1-git-send-email-kernelfans@gmail.com> References: <1560422702-11403-1-git-send-email-kernelfans@gmail.com> 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: FOLL_LONGTERM suggests a pin which is going to be given to hardware and can't move. It would truncate CMA permanently and should be excluded. FOLL_LONGTERM has already been checked in the slow path, but not checked in the fast path, which means a possible leak of CMA page to longterm pinned requirement through this crack. Place a check in gup_pte_range() in the fast path. Signed-off-by: Pingfan Liu Cc: Ira Weiny Cc: Andrew Morton Cc: Mike Rapoport Cc: Dan Williams Cc: Matthew Wilcox Cc: John Hubbard Cc: "Aneesh Kumar K.V" Cc: Keith Busch Cc: Christoph Hellwig Cc: Shuah Khan Cc: linux-kernel@vger.kernel.org --- mm/gup.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/mm/gup.c b/mm/gup.c index 766ae54..de1b03f 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1757,6 +1757,14 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, VM_BUG_ON(!pfn_valid(pte_pfn(pte))); page = pte_page(pte); + /* + * FOLL_LONGTERM suggests a pin given to hardware. Prevent it + * from truncating CMA area + */ + if (unlikely(flags & FOLL_LONGTERM) && + is_migrate_cma_page(page)) + goto pte_unmap; + head = try_get_compound_head(page, 1); if (!head) goto pte_unmap; @@ -1900,6 +1908,12 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, refs++; } while (addr += PAGE_SIZE, addr != end); + if (unlikely(flags & FOLL_LONGTERM) && + is_migrate_cma_page(page)) { + *nr -= refs; + return 0; + } + head = try_get_compound_head(pmd_page(orig), refs); if (!head) { *nr -= refs; @@ -1941,6 +1955,12 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, refs++; } while (addr += PAGE_SIZE, addr != end); + if (unlikely(flags & FOLL_LONGTERM) && + is_migrate_cma_page(page)) { + *nr -= refs; + return 0; + } + head = try_get_compound_head(pud_page(orig), refs); if (!head) { *nr -= refs; @@ -1978,6 +1998,12 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr, refs++; } while (addr += PAGE_SIZE, addr != end); + if (unlikely(flags & FOLL_LONGTERM) && + is_migrate_cma_page(page)) { + *nr -= refs; + return 0; + } + head = try_get_compound_head(pgd_page(orig), refs); if (!head) { *nr -= refs; -- 2.7.5