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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pRb5f-005tiD-V5; Mon, 13 Feb 2023 15:50:04 +0000 Date: Mon, 13 Feb 2023 15:50:03 +0000 From: Matthew Wilcox To: Alexandre Ghiti Cc: Marek Szyprowski , "Vishal Moola (Oracle)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Mike Kravetz Subject: Re: [PATCH 2/2] mm/khugepaged: Convert release_pte_pages() to use folios Message-ID: References: <20230114001556.43795-1-vishal.moola@gmail.com> <20230114001556.43795-2-vishal.moola@gmail.com> <3a3457b1-60bc-a97b-0042-432790d3bbbe@ghiti.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3a3457b1-60bc-a97b-0042-432790d3bbbe@ghiti.fr> X-Rspamd-Queue-Id: 52620A000F X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: z86udbrp9ziwzs4d7fjrc16g5hzcffmg X-HE-Tag: 1676303410-520751 X-HE-Meta: U2FsdGVkX1/pbcx6xHp6SK2nXD5gAcxDb27KpPYqEgFJ2QG7QrW/3yT9LdLev17XpSos64BqpF0hkytgtJ+Gq2/KJSfotr4gjtViqr4ZrG+k9d9Hvvepy5D0dMXyJRjKZTHIfBFeOce2kuzqCewHRro40R+guLcp/HNiTMoVv0e4XVqzhFBra35mPylbykFGiO5d7JQsIqpjzDbKIM/H5TTaC56QvRIMEKzS7/AsnS7Vn422j2J1vRrkXhXWT0PTXprC2Tizm51uetPFtV/yxMH4voPjJlDEYhLW0xrUZt2WkE3O5uLDJNx2DXkp7woVDfiBsfynV/ceEMUfk/Na1UtwNYPBRiDb6bL2p3Imrl85XjJRfGKwFZ0VX8zm61Mq1brL+ZwfjFFGEoOI/5VCj8YVedS+IO7wG9R0bmN4+nXs0v/7TOMj4TN6F/CxxFaYgVCigwmGXTSYWsX+xIHHdhN7r+2LwjxSyRqCBuAZzaRPszPSJcDKLul80gx56xln80ozM637/tmxgCrtekA9CSYqCo8qmyyTi/jEtF3iW+zlAem6+IU6N/lG5yQroW19q9OprGkl5FZ3dnuAkO/HvNcOrOfLGW824i1+ZhV+aOd+RpFDtYEfm9E05oAasV05T76DcbY+wiPNyTEmc5MJAHFZIgXMwy79MKzKjBL4DQQ7Vdmg64VJAXYEM11tYz2Ea3Q0Ip2E7RfX6wyVgeEVE9dSODXkRhJD/KPO7Fyd0GomLaN6iVWUhtIpQT+b8B3OBj9W/9m5nxe/SfctjbdnrkWQ/ZWb8w5Jea3qJtk6jHNn8uXq6yosAjOY/D0Umm0auqaeEGrQZr1NtUEK9wtnppttIRNzMmgJdeH3kOU6M7f3PKM1onwnO5kyAY12M5dxhdExiW0Eh612C/2rNC+ID0GTvSMhkJX7vSm77iMp7CjG0i/LRtqyy+ZalPFN7xCRn+KnqoXqGQiUT3Eh2si ZqEURHCu 7CdAJxusdOZy7OAHztnjxthGT3NwsuzQrUnRya6GE/u8d9P4OsFKo4/7ssx3mPg98E/eJ9XvsvZcUqT8oT240ktbC+Vnk/DZf1nFnorE2IQq3ZbYWPJIKR+Ey0RoMWgGvPDGE5DeRo+ci5vRLtPuHP6tQodUi1Xzde6b/OZc/dMVDD3thCmKz/n9REtHfwXFJALezulkQpCPF0WErETr0R/rYVGAcrokVGATWkVI5hURU5PMCJDV6KzhP/Z7vv3CCTBsmoBTeC8nSQzY= 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 Mon, Feb 13, 2023 at 04:28:05PM +0100, Alexandre Ghiti wrote: > The issue lies here: before using pteval in pfn_folio(), we should test it. > The following patch fixes the issue for me: Thanks for debugging it. I'd rather see this written as ... pte_t pteval = *_pte; + unsigned long pfn; + if (pte_none(pteval)) + continue; + pfn = pte_pfn(pteval); + if (is_zero_pfn(pfn)) + continue; + folio = pfn_folio(pfn); + if (folio_test_large(folio)) + continue; release_pte_folio(folio); makes sense? > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index eb38bd1b1b2f..fef3414b481b 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -514,10 +514,12 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte, >         while (--_pte >= pte) { >                 pte_t pteval = *_pte; > > -               folio = pfn_folio(pte_pfn(pteval)); > -               if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)) && > -                               !folio_test_large(folio)) > -                       release_pte_folio(folio); > +               if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) { > +                       folio = pfn_folio(pte_pfn(pteval)); > + > +                       if (!folio_test_large(folio)) > +                               release_pte_folio(folio); > +               } >         } > >         list_for_each_entry_safe(folio, tmp, compound_pagelist, lru) { > > > @Marek: could you give it a try? > > I can send a separate patch if needed, let me know. > > Thanks, > > Alex > > > > > if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)) && > > > - !PageCompound(page)) > > > - release_pte_page(page); > > > + !folio_test_large(folio)) > > > + release_pte_folio(folio); > > > } > > > - list_for_each_entry_safe(page, tmp, compound_pagelist, lru) { > > > - list_del(&page->lru); > > > - release_pte_page(page); > > > + list_for_each_entry_safe(folio, tmp, compound_pagelist, lru) { > > > + list_del(&folio->lru); > > > + release_pte_folio(folio); > > > } > > > } > > Best regards >