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Thu, 28 Jun 2018 17:38:05 -0700 (PDT) Received: from IN01WEHTCB.internal.synopsys.com (10.144.199.106) by US01WEHTC2.internal.synopsys.com (10.12.239.237) with Microsoft SMTP Server (TLS) id 14.3.361.1; Thu, 28 Jun 2018 17:38:05 -0700 Received: from IN01WEHTCA.internal.synopsys.com (10.144.199.103) by IN01WEHTCB.internal.synopsys.com (10.144.199.105) with Microsoft SMTP Server (TLS) id 14.3.361.1; Fri, 29 Jun 2018 06:08:02 +0530 Received: from [10.10.161.98] (10.10.161.98) by IN01WEHTCA.internal.synopsys.com (10.144.199.243) with Microsoft SMTP Server (TLS) id 14.3.361.1; Fri, 29 Jun 2018 06:08:02 +0530 Subject: Re: [PATCH] ARC: Fix __swp_offset() implementation To: Alexey Brodkin , "linux-snps-arc@lists.infradead.org" CC: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" References: <20180628235914.20706-1-abrodkin@synopsys.com> From: Vineet Gupta Openpgp: preference=signencrypt Autocrypt: addr=vgupta@synopsys.com; keydata= xsFNBFEffBMBEADIXSn0fEQcM8GPYFZyvBrY8456hGplRnLLFimPi/BBGFA24IR+B/Vh/EFk B5LAyKuPEEbR3WSVB1x7TovwEErPWKmhHFbyugdCKDv7qWVj7pOB+vqycTG3i16eixB69row lDkZ2RQyy1i/wOtHt8Kr69V9aMOIVIlBNjx5vNOjxfOLux3C0SRl1veA8sdkoSACY3McOqJ8 zR8q1mZDRHCfz+aNxgmVIVFN2JY29zBNOeCzNL1b6ndjU73whH/1hd9YMx2Sp149T8MBpkuQ cFYUPYm8Mn0dQ5PHAide+D3iKCHMupX0ux1Y6g7Ym9jhVtxq3OdUI5I5vsED7NgV9c8++baM 7j7ext5v0l8UeulHfj4LglTaJIvwbUrCGgtyS9haKlUHbmey/af1j0sTrGxZs1ky1cTX7yeF nSYs12GRiVZkh/Pf3nRLkjV+kH++ZtR1GZLqwamiYZhAHjo1Vzyl50JT9EuX07/XTyq/Bx6E dcJWr79ZphJ+mR2HrMdvZo3VSpXEgjROpYlD4GKUApFxW6RrZkvMzuR2bqi48FThXKhFXJBd JiTfiO8tpXaHg/yh/V9vNQqdu7KmZIuZ0EdeZHoXe+8lxoNyQPcPSj7LcmE6gONJR8ZqAzyk F5voeRIy005ZmJJ3VOH3Gw6Gz49LVy7Kz72yo1IPHZJNpSV5xwARAQABzS1WaW5lZXQgR3Vw dGEgKHBlcnNvbmFsKSA8dmluZWV0Zzc2QGdtYWlsLmNvbT7CwX4EEwECACgCGwMGCwkIBwMC BhUIAgkKCwQWAgMBAh4BAheABQJbBYpwBQkLx0HcAAoJEGnX8d3iisJe9TAP/3ljkSlRwToH O0E9QimJJqF52uZ0phSg1ZoavgHhGtz1mRykgeOzOITpFmYGBnf3v2Z33fDltIxTaN5TkRwl DjYvz1NTBlTLyPRbYwdCn6YyVSWj75hiGwdD0/N5M7Rb3XYsyDHvZ/tns1oGwipPmu9G+JoB VOkZw/bviE8AmGEK54PWdU1t3AnJ/3wtT6FSIPlTtCREiuZdQItjFkH0sYL1/BOXcE+XoBoQ 9hx6IEb46pop9ix/IRov2y6ZBUtDbF+SOSvImRadvD8A1ttvH51naP21Bra3ypV/GmZOR1/U 8azvgKmimYvC0345za/dS8eqrDuSh2IbEkDR0juQsFbkWS4IY5uqckzRWxHVZBas9CjpjipO C4iTzxq3CgmCyAD5qlQndJdhbsTgN18PXVAAI/phC1BtjNOoCgWgNsr8JK2TbXNF9wSR17T7 jDWCZ+Up8k5CTVQywLwJl91u5dV82WAnHnv3U1dwUX46DFMenV16ADfRrm7ib+D/O0XZMP7B sGC7PPleU+Ej/rt6V4H6VZ5RC9CXVCdUjM+ZZsqJc6/f5od4gSyswWQzCb/izU5ebxrehTUJ lPh2QCa6e46G1WzLWwZCFmQU3uUQtCXU1BBId/nL+Y3hQW0XKapvTx+zr8cZAZDXb83YE8Qs inBoGE5y9nj+ZveaVZHZRy63zsFNBFEffBMBEADXZ2pWw4Regpfw+V+Vr6tvZFRl245PV9rW FU72xNuvZKq/WE3xMu+ZE7l2JKpSjrEoeOHejtT0cILeQ/Yhf2t2xAlrBLlGOMmMYKK/K0Dc 2zf0MiPRbW/NCivMbGRZdhAAMx1bpVhInKjU/6/4mT7gcE57Ep0tl3HBfpxCK8RRlZc3v8BH OaEfcWSQD7QNTZK/kYJo+Oyux+fzyM5TTuKAaVE63NHCgWtFglH2vt2IyJ1XoPkAMueLXay6 enSKNci7qAG2UwicyVDCK9AtEub+ps8NakkeqdSkDRp5tQldJbfDaMXuWxJuPjfSojHIAbFq P6QaANXvTCSuBgkmGZ58skeNopasrJA4z7OsKRUBvAnharU82HGemtIa4Z83zotOGNdaBBOH NN2MHyfGLm+kEoccQheH+my8GtbH1a8eRBtxlk4c02ONkq1Vg1EbIzvgi4a56SrENFx4+4sZ cm8oItShAoKGIE/UCkj/jPlWqOcM/QIqJ2bR8hjBny83ONRf2O9nJuEYw9vZAPFViPwWG8tZ 7J+ReuXKai4DDr+8oFOi/40mIDe/Bat3ftyd+94Z1RxDCngd3Q85bw13t2ttNLw5eHufLIpo EyAhTCLNQ58eT91YGVGvFs39IuH0b8ovVvdkKGInCT59Vr0MtfgcsqpDxWQXJXYZYTFHd3/R swARAQABwsFlBBgBAgAPAhsMBQJbBYpwBQkLx0HdAAoJEGnX8d3iisJewe8P/36pkZrVTfO+ U+Gl1OQh4m6weozuI8Y98/DHLMxEujKAmRzy+zMHYlIl3WgSih1UMOZ7U84yVZQwXQkLItcw XoihChKD5D2BKnZYEOLM+7f9DuJuWhXpee80aNPzEaubBYQ7dYt8rcmB7SdRz/yZq3lALOrF /zb6SRleBh0DiBLP/jKUV74UAYV3OYEDHN9blvhWUEFFE0Z+j96M4/kuRdxvbDmp04Nfx79A mJEnfv1Vvc9CFiWVbBrNPKomIN+JV7a7m2lhbfhlLpUk0zGFDTWcWejl4qz/pCYSoIUU4r/V BsCVZrOun4vd4cSi/yYJRY4kaAJGCL5k7qhflL2tgldUs+wERH8ZCzimWVDBzHTBojz0Ff3w 2+gY6FUbAJBrBZANkymPpdAB/lTsl8D2ZRWyy90f4VVc8LB/QIWY/GiS2towRXQBjHOfkUB1 JiEXYH/i93k71mCaKfzKGXTVxObU2I441w7r4vtNlu0sADRHCMUqHmkpkjV1YbnYPvBPFrDB S1V9OfD9SutXeDjJYe3N+WaLRp3T3x7fYVnkfjQIjDSOdyPWlTzqQv0I3YlUk7KjFrh1rxtr poYSIQKf5HuMowUNtjyiK2VhA5V2XDqd+ZUT3RqfAPf3Y5HjkhKJRqoIDggUKMUKmXaxCkPG i91ThhqBJlyU6MVUa6vZNv8E Message-ID: <1406e091-d288-c5d6-5340-1bbca25d39c2@synopsys.com> Date: Thu, 28 Jun 2018 17:37:56 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180628235914.20706-1-abrodkin@synopsys.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.10.161.98] Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/28/2018 04:59 PM, Alexey Brodkin wrote: > We encode offset from swapcache page in __swp_entry() this way, see [1]: > | /* Encode swap {type,off} tuple into PTE > | * We reserve 13 bits for 5-bit @type, keeping bits 12-5 zero, ensuring that > | * PAGE_PRESENT is zero in a PTE holding swap "identifier" > | */ > | #define __swp_entry(type, off) ((swp_entry_t) { \ > | ((type) & 0x1f) | ((off) << 13) }) > > But decode in __swp_offset() as: > | #define __swp_offset(pte_lookalike) ((pte_lookalike).val << 13) > which is obviously wrong, we should ">> 13" instead. > > This basically fixes swap usage on ARC finally. Nice. Wish all fixes were so simple ;-) I've added this to for-curr and will also make its way to stable, but lets clean up this mess of hardcoded 13 properly as a cleanup patch. There are good references to look at : arm, riscv etc Thx, -Vineet