From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 97E77EC5 for ; Thu, 8 Jun 2023 02:12:34 +0000 (UTC) Received: from loongson.cn (unknown [10.180.13.185]) by gateway (Coremail) with SMTP id _____8CxPusKOYFkFVIAAA--.1210S3; Thu, 08 Jun 2023 10:12:26 +0800 (CST) Received: from [10.180.13.185] (unknown [10.180.13.185]) by localhost.localdomain (Coremail) with SMTP id AQAAf8DxluQJOYFkgDoGAA--.20361S3; Thu, 08 Jun 2023 10:12:25 +0800 (CST) Subject: Re: [PATCH] LoongArch: let pmd_present return true when splitting pmd To: Anshuman Khandual Cc: Huacai Chen , WANG Xuerui , Andrew Morton , David Hildenbrand , Mike Rapoport , Jiaxun Yang , Feiyang Chen , Qi Zheng , loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, loongson-kernel@lists.loongnix.cn References: <20230524074132.10916-1-zhanghongchen@loongson.cn> From: Hongchen Zhang Message-ID: Date: Thu, 8 Jun 2023 10:12:25 +0800 User-Agent: Mozilla/5.0 (X11; Linux loongarch64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 Precedence: bulk X-Mailing-List: loongarch@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-CM-TRANSID:AQAAf8DxluQJOYFkgDoGAA--.20361S3 X-CM-SenderInfo: x2kd0w5krqwupkhqwqxorr0wxvrqhubq/1tbiAQAQB2SAc4ELCwAAsA X-Coremail-Antispam: 1Uk129KBj93XoWxJw48CFWUJF18CFW7Zw15ZFc_yoW5ur15p3 Z7CF1kCrW5KFyfC34aqF13ZFyUZrsrKFn2gryqgw1UAF9xX397Xrn5Krn8AFyrXayvyFy8 Wr4qgw15WFW3t3cCm3ZEXasCq-sJn29KB7ZKAUJUUUU7529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUP2b4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Gr0_Xr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVWxJVW8Jr1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6r4j6r4UJwAaw2AFwI0_Jrv_JF1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqjxCEc2xF0c Ia020Ex4CE44I27wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_JF0_ Jw1lYx0Ex4A2jsIE14v26r4j6F4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvEwIxGrw CYjI0SjxkI62AI1cAE67vIY487MxkF7I0En4kS14v26r126r1DMxAIw28IcxkI7VAKI48J MxC20s026xCaFVCjc4AY6r1j6r4UMxCIbckI1I0E14v26r1Y6r17MI8I3I0E5I8CrVAFwI 0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y 0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxV WUJVW8JwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1l IxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU0b6pPUUUU U== Hi Anshuman, On 2023/5/27 下午1:32, Huacai Chen wrote: > Hi, Anshuman, > > Excuse me, but could you please tell me something that why commit > b65399f6111b ("arm64/mm: Change THP helpers to comply with generic MM > semantics") needn't be backported to 5.4LTS and 4.19LTS series. The > discussion link you referred is as early as in 2018, before 4.19 > released. I think this information is important for us because we want > to know how to handle our 4.19-loongarch codebase. What's your opinion about huacai's question? In my opinion,your commit should be backported to 5.4LTS and 4.19LTS. > > Huacai > > On Wed, May 24, 2023 at 3:42 PM Hongchen Zhang > wrote: >> >> when we split a pmd into ptes, pmd_present() and pmd_trans_huge() should >> return true,otherwise it would be treated as a swap pmd. >> As arm64 does in >> commit b65399f6111b ("arm64/mm: Change THP helpers to comply with generic MM semantics") >> we add a _PAGE_PRESENT_INVALID bit for LoongArch. >> >> Signed-off-by: Hongchen Zhang >> --- >> arch/loongarch/include/asm/pgtable-bits.h | 2 ++ >> arch/loongarch/include/asm/pgtable.h | 3 ++- >> 2 files changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/arch/loongarch/include/asm/pgtable-bits.h b/arch/loongarch/include/asm/pgtable-bits.h >> index 8b98d22a145b..a7469d28d9d0 100644 >> --- a/arch/loongarch/include/asm/pgtable-bits.h >> +++ b/arch/loongarch/include/asm/pgtable-bits.h >> @@ -22,12 +22,14 @@ >> #define _PAGE_PFN_SHIFT 12 >> #define _PAGE_SWP_EXCLUSIVE_SHIFT 23 >> #define _PAGE_PFN_END_SHIFT 48 >> +#define _PAGE_PRESENT_INVALID_SHIFT 60 >> #define _PAGE_NO_READ_SHIFT 61 >> #define _PAGE_NO_EXEC_SHIFT 62 >> #define _PAGE_RPLV_SHIFT 63 >> >> /* Used by software */ >> #define _PAGE_PRESENT (_ULCAST_(1) << _PAGE_PRESENT_SHIFT) >> +#define _PAGE_PRESENT_INVALID (_ULCAST_(1) << _PAGE_PRESENT_INVALID_SHIFT) >> #define _PAGE_WRITE (_ULCAST_(1) << _PAGE_WRITE_SHIFT) >> #define _PAGE_ACCESSED (_ULCAST_(1) << _PAGE_ACCESSED_SHIFT) >> #define _PAGE_MODIFIED (_ULCAST_(1) << _PAGE_MODIFIED_SHIFT) >> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h >> index d28fb9dbec59..9a9f9ff9b709 100644 >> --- a/arch/loongarch/include/asm/pgtable.h >> +++ b/arch/loongarch/include/asm/pgtable.h >> @@ -213,7 +213,7 @@ static inline int pmd_bad(pmd_t pmd) >> static inline int pmd_present(pmd_t pmd) >> { >> if (unlikely(pmd_val(pmd) & _PAGE_HUGE)) >> - return !!(pmd_val(pmd) & (_PAGE_PRESENT | _PAGE_PROTNONE)); >> + return !!(pmd_val(pmd) & (_PAGE_PRESENT | _PAGE_PROTNONE | _PAGE_PRESENT_INVALID)); >> >> return pmd_val(pmd) != (unsigned long)invalid_pte_table; >> } >> @@ -558,6 +558,7 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) >> >> static inline pmd_t pmd_mkinvalid(pmd_t pmd) >> { >> + pmd_val(pmd) |= _PAGE_PRESENT_INVALID; >> pmd_val(pmd) &= ~(_PAGE_PRESENT | _PAGE_VALID | _PAGE_DIRTY | _PAGE_PROTNONE); >> >> return pmd; >> >> base-commit: f1fcbaa18b28dec10281551dfe6ed3a3ed80e3d6 >> -- >> 2.31.1 >> >> Best Regards Hongchen Zhang