From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9FE34C54798 for ; Tue, 27 Feb 2024 09:20:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 19735940012; Tue, 27 Feb 2024 04:20:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 11ECC940008; Tue, 27 Feb 2024 04:20:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EDCF0940012; Tue, 27 Feb 2024 04:20:23 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id C4293940008 for ; Tue, 27 Feb 2024 04:20:23 -0500 (EST) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 9F01A1A0123 for ; Tue, 27 Feb 2024 09:20:23 +0000 (UTC) X-FDA: 81837037926.25.B555F40 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf28.hostedemail.com (Postfix) with ESMTP id DA2A1C0002 for ; Tue, 27 Feb 2024 09:20:21 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf28.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1709025622; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=H9BW5XVAe0LjVozXypILw+BakFXNN+uGbpaSq7NiCSM=; b=JeDTHmnRhwcfz2ZBka4gcWMAKIhllZlg4ADCPd3bxH8twW5O5kOUZaCdFuzJpzNuxdoC6O q1zpktRcuFL8f/0yVvAHmVxIcTblxBsZqHcpriP2aItS5EFItoKXhZFQAztjUZzvzaWFcw yCuRANbqDoAEoBzT6jMopvhTK25gm9w= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf28.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1709025622; a=rsa-sha256; cv=none; b=6d9FJchMYpTPneJTui3kVTwFOnMX8keW+oPPth4APhzHiXui3hWGr3d4513TAK5Oln6H0U OkdHJ/c99zkCgFPpkWYm5+Wud6IrirrJVp6Zs/xOp1tH7j2TQs215nPYUv5Hnj9fkf8WU0 xGOBI4NZ/3JLivb6VWumAnDPvfuVD8o= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 39A40DA7; Tue, 27 Feb 2024 01:20:59 -0800 (PST) Received: from [10.57.67.4] (unknown [10.57.67.4]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A75833F762; Tue, 27 Feb 2024 01:20:18 -0800 (PST) Message-ID: <74958d41-6d73-4f5a-aae7-33dc374b6ddb@arm.com> Date: Tue, 27 Feb 2024 09:20:16 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: export folio_pte_batch as a couple of modules might need it Content-Language: en-GB To: David Hildenbrand , Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Barry Song , Lance Yang , Yin Fengwei References: <20240227024050.244567-1-21cnbao@gmail.com> <61b9dfc9-5522-44fd-89a4-140833ede8af@arm.com> From: Ryan Roberts In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: DA2A1C0002 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: tuh1iusp8bp6hoa636ie4a3pas6wkqn9 X-HE-Tag: 1709025621-10839 X-HE-Meta: U2FsdGVkX19fVtzjM3QX/JLM/LXBt8IfvglRHL8JmVPcijurp47aM6kbM0w5LmyRwH8fWaW1FrmwTpBEcmVC3xLaHclaUdXwDW8b+K0bSn3MXcEr632nklrDvu6uEr1kdxIER0bdkfxUmxirXE6meb1YPu2Myoi0pz6+yyxMIvKH4jKBklVqc4GwEXFKU5pUGPMcthFiE4eHDLsMqSPn8ZGQugkgVVtKdqrpj0ITFLWNzUDS9MJ2AXN/Q7KZ9U3HFojU/yWxIfqQHtpG0HwG80tf+i7doXnbu3wiOzq1N1F1y9YSEbOH1JILtdFWLfYqMz7nS8zgXq94w08aSJuehlPqr80bc4WBmHM7k3l5jgsYYuvBTS885pcVzfSTVSt3MA31d4gur9p/ZBNIdetr2BXM6M2nOSQqL6GTCYbmHuLX1oBF9o1dJwrq77YtJ06rN9G6klJ0V2AETncIrhbBucYGMHQq9kZXYnZEFuMWiwHi1diHFmlUcmS7+TzWtXrJtpLjRj3WO23SIz7Z5C0G3dmUWj+RVsPI9F8Xjumw5Kl1u6ujE2kCSg0O+2XZZXR+Bz2SBsrG3Pp7Y84mLhVBGOAmLIunK+1hi3RHqS21x/9AQaq00fI7Ov0UVdM0aW9jYALg2ko7hw21ajwSW8Je3mIPbKxnIJo4u24/GaAH1LrNveaduuQKWLqv7mUrbs5lbZaPEo7XTkHECjvqPfxpih83prStBHkcla6e7wqAae4QDRtIXXBH4e32fMw8FWenM67LF10Q9HW13w7U4znzSE3lH+4XuD1S0xZQhP4y7Rf9D0+KqG4EiArn/bVJbBEazjJHOMUzj/ceCGbVzo71CCj0GFDzgPNK3/pcxQ2HyoZq/oDEN67/3P8kFTVrNZgxdaIfPCksu2Q= 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: List-Subscribe: List-Unsubscribe: On 27/02/2024 09:14, David Hildenbrand wrote: > On 27.02.24 10:07, Ryan Roberts wrote: >> On 27/02/2024 02:40, Barry Song wrote: >>> From: Barry Song >>> >>> madvise and some others might need folio_pte_batch to check if a range >>> of PTEs are completely mapped to a large folio with contiguous physcial >>> addresses. Let's export it for others to use. >>> >>> Cc: Lance Yang >>> Cc: Ryan Roberts >>> Cc: David Hildenbrand >>> Cc: Yin Fengwei >>> Signed-off-by: Barry Song >>> --- >>>   -v1: >>>   at least two jobs madv_free and madv_pageout depend on it. To avoid >>>   conflicts and dependencies, after discussing with Lance, we prefer >>>   this one can land earlier. >> >> I think this will also ultimately be useful for mprotect too, though I haven't >> looked at it properly yet. >> > > Yes, I think we briefly discussed that. > >>> >>>   mm/internal.h | 13 +++++++++++++ >>>   mm/memory.c   | 11 +---------- >>>   2 files changed, 14 insertions(+), 10 deletions(-) >>> >>> diff --git a/mm/internal.h b/mm/internal.h >>> index 13b59d384845..8e2bc304f671 100644 >>> --- a/mm/internal.h >>> +++ b/mm/internal.h >>> @@ -83,6 +83,19 @@ static inline void *folio_raw_mapping(struct folio *folio) >>>       return (void *)(mapping & ~PAGE_MAPPING_FLAGS); >>>   } >>>   +/* Flags for folio_pte_batch(). */ >>> +typedef int __bitwise fpb_t; >>> + >>> +/* Compare PTEs after pte_mkclean(), ignoring the dirty bit. */ >>> +#define FPB_IGNORE_DIRTY        ((__force fpb_t)BIT(0)) >>> + >>> +/* Compare PTEs after pte_clear_soft_dirty(), ignoring the soft-dirty bit. */ >>> +#define FPB_IGNORE_SOFT_DIRTY        ((__force fpb_t)BIT(1)) >>> + >>> +extern int folio_pte_batch(struct folio *folio, unsigned long addr, >>> +        pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags, >>> +        bool *any_writable); >>> + >>>   void __acct_reclaim_writeback(pg_data_t *pgdat, struct folio *folio, >>>                           int nr_throttled); >>>   static inline void acct_reclaim_writeback(struct folio *folio) >>> diff --git a/mm/memory.c b/mm/memory.c >>> index 1c45b6a42a1b..319b3be05e75 100644 >>> --- a/mm/memory.c >>> +++ b/mm/memory.c >>> @@ -953,15 +953,6 @@ static __always_inline void __copy_present_ptes(struct >>> vm_area_struct *dst_vma, >>>       set_ptes(dst_vma->vm_mm, addr, dst_pte, pte, nr); >>>   } >>>   -/* Flags for folio_pte_batch(). */ >>> -typedef int __bitwise fpb_t; >>> - >>> -/* Compare PTEs after pte_mkclean(), ignoring the dirty bit. */ >>> -#define FPB_IGNORE_DIRTY        ((__force fpb_t)BIT(0)) >>> - >>> -/* Compare PTEs after pte_clear_soft_dirty(), ignoring the soft-dirty bit. */ >>> -#define FPB_IGNORE_SOFT_DIRTY        ((__force fpb_t)BIT(1)) >>> - >>>   static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) >>>   { >>>       if (flags & FPB_IGNORE_DIRTY) >>> @@ -982,7 +973,7 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, >>> fpb_t flags) >>>    * If "any_writable" is set, it will indicate if any other PTE besides the >>>    * first (given) PTE is writable. >>>    */ >> >> David was talking in Lance's patch thread, about improving the docs for this >> function now that its exported. Might be worth syncing on that. > > Here is my take: > > Signed-off-by: David Hildenbrand > --- >  mm/memory.c | 22 ++++++++++++++++++---- >  1 file changed, 18 insertions(+), 4 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index d0b855a1837a8..098356b8805ae 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -971,16 +971,28 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, > fpb_t flags) >      return pte_wrprotect(pte_mkold(pte)); >  } >   > -/* > +/** > + * folio_pte_batch - detect a PTE batch for a large folio > + * @folio: The large folio to detect a PTE batch for. > + * @addr: The user virtual address the first page is mapped at. > + * @start_ptep: Page table pointer for the first entry. > + * @pte: Page table entry for the first page. > + * @max_nr: The maximum number of table entries to consider. > + * @flags: Flags to modify the PTE batch semantics. > + * @any_writable: Optional pointer to indicate whether any entry except the > + *          first one is writable. > + * >   * Detect a PTE batch: consecutive (present) PTEs that map consecutive > - * pages of the same folio. > + * pages of the same large folio. >   * >   * All PTEs inside a PTE batch have the same PTE bits set, excluding the PFN, >   * the accessed bit, writable bit, dirty bit (with FPB_IGNORE_DIRTY) and >   * soft-dirty bit (with FPB_IGNORE_SOFT_DIRTY). >   * > - * If "any_writable" is set, it will indicate if any other PTE besides the > - * first (given) PTE is writable. > + * start_ptep must map any page of the folio. max_nr must be at least one and > + * must be limited by the caller so scanning cannot exceed a single page table. > + * > + * Return: the number of table entries in the batch. >   */ LGTM! >  static inline int folio_pte_batch(struct folio *folio, unsigned long addr, >          pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags, > @@ -996,6 +1008,8 @@ static inline int folio_pte_batch(struct folio *folio, > unsigned long addr, >          *any_writable = false; >   >      VM_WARN_ON_FOLIO(!pte_present(pte), folio); > +    VM_WARN_ON_FOLIO(!folio_test_large(folio) || max_nr < 1, folio); > +    VM_WARN_ON_FOLIO(page_folio(pfn_to_page(pte_pfn(pte))) != folio, folio); >   >      nr = pte_batch_hint(start_ptep, pte); >      expected_pte = __pte_batch_clear_ignored(pte_advance_pfn(pte, nr), flags);