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 4A9A9C7EE25 for ; Thu, 18 May 2023 17:13:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ACC7F280001; Thu, 18 May 2023 13:13:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A547B900003; Thu, 18 May 2023 13:13:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8F6A2280001; Thu, 18 May 2023 13:13:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 7E398900003 for ; Thu, 18 May 2023 13:13:30 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 467711C766C for ; Thu, 18 May 2023 17:13:30 +0000 (UTC) X-FDA: 80804022180.30.5B5B193 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf04.hostedemail.com (Postfix) with ESMTP id 6FA8740009 for ; Thu, 18 May 2023 17:13:27 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=l3PfBzrG; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf04.hostedemail.com: domain of sj@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=sj@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1684430007; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=c74cXvTqG04S3yLNO1wsqCYvyz8qN5QRVbKvcgQCRJQ=; b=3avyIMab/yOdgdmtxn2v39cXndy65rclmgOuxAFFU7WNBReoDRoubgcrN3dDWvAWSADwoz 3uePFznsrj4KcwP5XzFm3Lg11ThEs1eY7CKhoE29O0THNYLC5YvvViKmOobK1i3e/f2FLA SML/35r4qu4V7bW9FEX5VY7ebzjwBPY= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=l3PfBzrG; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf04.hostedemail.com: domain of sj@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=sj@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1684430007; a=rsa-sha256; cv=none; b=wmrB2lifJRhVcHGiecMs5sJrefSuxPgTlXFIbNTYTfbjBW1lYIs+1SPPFl8tr0TY9/Z9Cm yvyU9vVOu6WQL+qKSIzXzrevZQG821mzx8ZjQK6nByh31tuOvaqJucObK+bpAgmYf+CacH TdKNb4IL1+kHj20XWcVQ8nR67Rh6NCk= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 60C1F61CD9; Thu, 18 May 2023 17:13:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DDA92C433EF; Thu, 18 May 2023 17:13:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684430005; bh=/DBLWf58+j65eoP2xEHnqealzR5M1KHu1Lqk9ywqqZw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l3PfBzrGW/KmSu63/LtrZ8aR70wDbxTz7tU220EljMmlebE6Mgj4ebjppPwci1r+N hB7kZ0ybwN9rd/CdhorR27+GsfpmmU3tP6xRqM50WsVAlJeosPTGdLSC3kLwt2IFaw GOIeqa0UwVAg1KtSluKOtjYfU7weRVxXVnIaxUtskRT2+k3Un/kBvM4sdGZbtERtyT 3LPjZxfG0Zn/BAfSJpL60ZJxiD+f3ctvAJCXxxBhjm8LieSD/7hH9ortJqAliQ7blD PikY4RpAb3O/uD6lHYzcVLkuOahnx7FMP6sJOcVTfjB/OJ54MFjoenmuZsmaANOjQz OR14s6Ptff+AA== From: SeongJae Park To: Ryan Roberts Cc: Andrew Morton , SeongJae Park , Christoph Hellwig , "Matthew Wilcox (Oracle)" , "Kirill A. Shutemov" , Lorenzo Stoakes , Uladzislau Rezki , Zi Yan , linux-kernel@vger.kernel.org, linux-mm@kvack.org, damon@lists.linux.dev Subject: Re: [PATCH v2 2/5] mm: damon must atomically clear young on ptes and pmds Date: Thu, 18 May 2023 17:13:23 +0000 Message-Id: <20230518171323.83828-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230518110727.2106156-3-ryan.roberts@arm.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 6FA8740009 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: qawfhwsrtbd8oidkgjyn6dokhph8ztot X-HE-Tag: 1684430007-186297 X-HE-Meta: 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 7WJ2U3+l iuvtBI7Xo99OerQcsYKI2ue0MztwoDiKWDEANGARinF8jWEdsSp8fk+P8TUt2KpMqBH8bqlaDI7jzgptwtnc4+NC4zZK93nazYJP7DzLYsabXvvghxfSbCxeFf6FH3Q5uMp4OoP51sBBT6u9rg5phE9QOPBwCJs09VLP//bD1tqi4/WiYzjSwKapzUmUYxn8PizbGBqMt9fh9uU5hJhZGa7Suw2B7GJjGWySGHqD0NQ91ibeeWKUPDRJFHxRarW4fGl9z/MKkcdmt6xEOj2ZWYtzC/Z+lJg7fDwpE8+fgv2mTJNwlEPHHWA9HKUg182/WBu1A4K2a8PWMBjRJQLp8EqtMcQI5LPe3T9VypeShpqcy7n5edFco8vabNgfETu9axhRCyYr6gYh/EiG3zLlfzVpTr+MOR/cNmPImJXe+pFTijnI= 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: Hi Ryan, Nit. For consistency of DAMON commits subjects, I'd prefer something like "mm/damon/ops-common: atomically test and clear young on ptes and pmds". On Thu, 18 May 2023 12:07:24 +0100 Ryan Roberts wrote: > It is racy to non-atomically read a pte, then clear the young bit, then > write it back as this could discard dirty information. Further, it is > bad practice to directly set a pte entry within a table. Instead > clearing young must go through the arch-provided helper, > ptep_test_and_clear_young() to ensure it is modified atomically and to > give the arch code visibility and allow it to check (and potentially > modify) the operation. > > Fixes: 46c3a0accdc4 ("mm/damon/vaddr: separate commonly usable functions") Nit. The commit is only for refactoring. The original code camde from commit 3f49584b262c ("mm/damon: implement primitives for the virtual memory address spaces"). > Signed-off-by: Ryan Roberts > Reviewed-by: Zi Yan Other than above nits, Reviewed-by: SeongJae Park Thanks, SJ > --- > mm/damon/ops-common.c | 16 ++++++---------- > mm/damon/ops-common.h | 4 ++-- > mm/damon/paddr.c | 4 ++-- > mm/damon/vaddr.c | 4 ++-- > 4 files changed, 12 insertions(+), 16 deletions(-) > > diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c > index cc63cf953636..acc264b97903 100644 > --- a/mm/damon/ops-common.c > +++ b/mm/damon/ops-common.c > @@ -37,7 +37,7 @@ struct folio *damon_get_folio(unsigned long pfn) > return folio; > } > > -void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr) > +void damon_ptep_mkold(pte_t *pte, struct vm_area_struct *vma, unsigned long addr) > { > bool referenced = false; > struct folio *folio = damon_get_folio(pte_pfn(*pte)); > @@ -45,13 +45,11 @@ void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr) > if (!folio) > return; > > - if (pte_young(*pte)) { > + if (ptep_test_and_clear_young(vma, addr, pte)) > referenced = true; > - *pte = pte_mkold(*pte); > - } > > #ifdef CONFIG_MMU_NOTIFIER > - if (mmu_notifier_clear_young(mm, addr, addr + PAGE_SIZE)) > + if (mmu_notifier_clear_young(vma->vm_mm, addr, addr + PAGE_SIZE)) > referenced = true; > #endif /* CONFIG_MMU_NOTIFIER */ > > @@ -62,7 +60,7 @@ void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr) > folio_put(folio); > } > > -void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr) > +void damon_pmdp_mkold(pmd_t *pmd, struct vm_area_struct *vma, unsigned long addr) > { > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > bool referenced = false; > @@ -71,13 +69,11 @@ void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr) > if (!folio) > return; > > - if (pmd_young(*pmd)) { > + if (pmdp_test_and_clear_young(vma, addr, pmd)) > referenced = true; > - *pmd = pmd_mkold(*pmd); > - } > > #ifdef CONFIG_MMU_NOTIFIER > - if (mmu_notifier_clear_young(mm, addr, addr + HPAGE_PMD_SIZE)) > + if (mmu_notifier_clear_young(vma->vm_mm, addr, addr + HPAGE_PMD_SIZE)) > referenced = true; > #endif /* CONFIG_MMU_NOTIFIER */ > > diff --git a/mm/damon/ops-common.h b/mm/damon/ops-common.h > index 14f4bc69f29b..18d837d11bce 100644 > --- a/mm/damon/ops-common.h > +++ b/mm/damon/ops-common.h > @@ -9,8 +9,8 @@ > > struct folio *damon_get_folio(unsigned long pfn); > > -void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr); > -void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr); > +void damon_ptep_mkold(pte_t *pte, struct vm_area_struct *vma, unsigned long addr); > +void damon_pmdp_mkold(pmd_t *pmd, struct vm_area_struct *vma, unsigned long addr); > > int damon_cold_score(struct damon_ctx *c, struct damon_region *r, > struct damos *s); > diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c > index 467b99166b43..5b3a3463d078 100644 > --- a/mm/damon/paddr.c > +++ b/mm/damon/paddr.c > @@ -24,9 +24,9 @@ static bool __damon_pa_mkold(struct folio *folio, struct vm_area_struct *vma, > while (page_vma_mapped_walk(&pvmw)) { > addr = pvmw.address; > if (pvmw.pte) > - damon_ptep_mkold(pvmw.pte, vma->vm_mm, addr); > + damon_ptep_mkold(pvmw.pte, vma, addr); > else > - damon_pmdp_mkold(pvmw.pmd, vma->vm_mm, addr); > + damon_pmdp_mkold(pvmw.pmd, vma, addr); > } > return true; > } > diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c > index 1fec16d7263e..37994fb6120c 100644 > --- a/mm/damon/vaddr.c > +++ b/mm/damon/vaddr.c > @@ -311,7 +311,7 @@ static int damon_mkold_pmd_entry(pmd_t *pmd, unsigned long addr, > } > > if (pmd_trans_huge(*pmd)) { > - damon_pmdp_mkold(pmd, walk->mm, addr); > + damon_pmdp_mkold(pmd, walk->vma, addr); > spin_unlock(ptl); > return 0; > } > @@ -323,7 +323,7 @@ static int damon_mkold_pmd_entry(pmd_t *pmd, unsigned long addr, > pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); > if (!pte_present(*pte)) > goto out; > - damon_ptep_mkold(pte, walk->mm, addr); > + damon_ptep_mkold(pte, walk->vma, addr); > out: > pte_unmap_unlock(pte, ptl); > return 0; > -- > 2.25.1 > >