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Fri, 14 Aug 2020 22:31:06 -0800 Received: from MTKMBS02N1.mediatek.inc (172.21.101.77) by MTKMBS62N2.mediatek.inc (172.29.193.42) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 14 Aug 2020 23:21:05 -0700 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs02n1.mediatek.inc (172.21.101.77) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sat, 15 Aug 2020 14:20:52 +0800 Received: from mtkswgap22.mediatek.inc (172.21.77.33) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Sat, 15 Aug 2020 14:20:53 +0800 From: Chinwen Chang To: Matthias Brugger , Michel Lespinasse , Andrew Morton , "Vlastimil Babka" , Daniel Jordan , "Davidlohr Bueso" , Chinwen Chang , "Alexey Dobriyan" , "Matthew Wilcox (Oracle)" , Jason Gunthorpe , Steven Price , Song Liu , Jimmy Assarsson , Huang Ying , Daniel Kiss , Laurent Dufour Subject: [PATCH v3 1/3] mmap locking API: add mmap_lock_is_contended() Date: Sat, 15 Aug 2020 14:20:17 +0800 Message-ID: <1597472419-32314-2-git-send-email-chinwen.chang@mediatek.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1597472419-32314-1-git-send-email-chinwen.chang@mediatek.com> References: <1597472419-32314-1-git-send-email-chinwen.chang@mediatek.com> MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200815_023109_579248_AB95C977 X-CRM114-Status: GOOD ( 12.92 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.0 MIME_BASE64_TEXT RAW: Message text disguised using base64 encoding -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.0 UNPARSEABLE_RELAY Informational: message has unparseable relay lines X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-fsdevel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, wsd_upstream@mediatek.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Add new API to query if someone wants to acquire mmap_lock for write attempts. Using this instead of rwsem_is_contended makes it more tolerant of future changes to the lock type. Signed-off-by: Chinwen Chang Reviewed-by: Steven Price Acked-by: Michel Lespinasse --- include/linux/mmap_lock.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h index 0707671..18e7eae 100644 --- a/include/linux/mmap_lock.h +++ b/include/linux/mmap_lock.h @@ -87,4 +87,9 @@ static inline void mmap_assert_write_locked(struct mm_struct *mm) VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm); } +static inline int mmap_lock_is_contended(struct mm_struct *mm) +{ + return rwsem_is_contended(&mm->mmap_lock); +} + #endif /* _LINUX_MMAP_LOCK_H */ From patchwork Sat Aug 15 06:20:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chinwen Chang X-Patchwork-Id: 11715343 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 01C1B109B for ; Sat, 15 Aug 2020 06:21:59 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CEFF422DCC for ; 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bh=nO/7d3LEyww/DsobxJb7EoQeEP0stM9QgmRFbsqBnvA=; b=BZNOv1HI0yeXjrpNrg7r6TQe9gZp6wA/E4muyxAOlKyisGzjruMNmd97+k8jsE8sVP1WaSBEQLA/lLLcK7qJRIMlsUjUbzfx4cC9CfFTJohZff8qFda2F/eGiwLuNaUltgxQPZmJ+WBlnSUq9xF6EF83G8WUHsUI6MAfBa9YuDY=; X-UUID: 6d6f27d5964f4a2288d5694aded2c77c-20200814 Received: from mtkcas66.mediatek.inc [(172.29.193.44)] by mailgw01.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLS) with ESMTP id 81566228; Fri, 14 Aug 2020 22:21:06 -0800 Received: from MTKMBS02N2.mediatek.inc (172.21.101.101) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 14 Aug 2020 23:21:07 -0700 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs02n2.mediatek.inc (172.21.101.101) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sat, 15 Aug 2020 14:20:52 +0800 Received: from mtkswgap22.mediatek.inc (172.21.77.33) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Sat, 15 Aug 2020 14:20:54 +0800 From: Chinwen Chang To: Matthias Brugger , Michel Lespinasse , Andrew Morton , "Vlastimil Babka" , Daniel Jordan , "Davidlohr Bueso" , Chinwen Chang , "Alexey Dobriyan" , "Matthew Wilcox (Oracle)" , Jason Gunthorpe , Steven Price , Song Liu , Jimmy Assarsson , Huang Ying , Daniel Kiss , Laurent Dufour Subject: [PATCH v3 2/3] mm: smaps*: extend smap_gather_stats to support specified beginning Date: Sat, 15 Aug 2020 14:20:18 +0800 Message-ID: <1597472419-32314-3-git-send-email-chinwen.chang@mediatek.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1597472419-32314-1-git-send-email-chinwen.chang@mediatek.com> References: <1597472419-32314-1-git-send-email-chinwen.chang@mediatek.com> MIME-Version: 1.0 X-TM-SNTS-SMTP: 0920E33D6D0ECC02A6813D53E444A733A6F2A6B877A2FAD56C7ECAA86B5046E62000:8 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200815_022118_250189_3993DDA9 X-CRM114-Status: GOOD ( 18.28 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.0 MIME_BASE64_TEXT RAW: Message text disguised using base64 encoding -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.0 UNPARSEABLE_RELAY Informational: message has unparseable relay lines X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-fsdevel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, wsd_upstream@mediatek.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Extend smap_gather_stats to support indicated beginning address at which it should start gathering. To achieve the goal, we add a new parameter @start assigned by the caller and try to refactor it for simplicity. If @start is 0, it will use the range of @vma for gathering. Change since v2: - This is a new change to make the retry behavior of smaps_rollup - more complete as suggested by Michel [1] [1] https://lore.kernel.org/lkml/CANN689FtCsC71cjAjs0GPspOhgo_HRj+diWsoU1wr98YPktgWg@mail.gmail.com/ Signed-off-by: Chinwen Chang CC: Michel Lespinasse CC: Steven Price Reviewed-by: Steven Price --- fs/proc/task_mmu.c | 30 ++++++++++++++++++++++-------- 1 file changed, 22 insertions(+), 8 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index dbda449..76e623a 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -723,9 +723,21 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask, .pte_hole = smaps_pte_hole, }; +/* + * Gather mem stats from @vma with the indicated beginning + * address @start, and keep them in @mss. + * + * Use vm_start of @vma as the beginning address if @start is 0. + */ static void smap_gather_stats(struct vm_area_struct *vma, - struct mem_size_stats *mss) + struct mem_size_stats *mss, unsigned long start) { + const struct mm_walk_ops *ops = &smaps_walk_ops; + + /* Invalid start */ + if (start >= vma->vm_end) + return; + #ifdef CONFIG_SHMEM /* In case of smaps_rollup, reset the value from previous vma */ mss->check_shmem_swap = false; @@ -742,18 +754,20 @@ static void smap_gather_stats(struct vm_area_struct *vma, */ unsigned long shmem_swapped = shmem_swap_usage(vma); - if (!shmem_swapped || (vma->vm_flags & VM_SHARED) || - !(vma->vm_flags & VM_WRITE)) { + if (!start && (!shmem_swapped || (vma->vm_flags & VM_SHARED) || + !(vma->vm_flags & VM_WRITE))) { mss->swap += shmem_swapped; } else { mss->check_shmem_swap = true; - walk_page_vma(vma, &smaps_shmem_walk_ops, mss); - return; + ops = &smaps_shmem_walk_ops; } } #endif /* mmap_lock is held in m_start */ - walk_page_vma(vma, &smaps_walk_ops, mss); + if (!start) + walk_page_vma(vma, ops, mss); + else + walk_page_range(vma->vm_mm, start, vma->vm_end, ops, mss); } #define SEQ_PUT_DEC(str, val) \ @@ -805,7 +819,7 @@ static int show_smap(struct seq_file *m, void *v) memset(&mss, 0, sizeof(mss)); - smap_gather_stats(vma, &mss); + smap_gather_stats(vma, &mss, 0); show_map_vma(m, vma); @@ -854,7 +868,7 @@ static int show_smaps_rollup(struct seq_file *m, void *v) hold_task_mempolicy(priv); for (vma = priv->mm->mmap; vma; vma = vma->vm_next) { - smap_gather_stats(vma, &mss); + smap_gather_stats(vma, &mss, 0); last_vma_end = vma->vm_end; } From patchwork Sat Aug 15 06:20:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chinwen Chang X-Patchwork-Id: 11715351 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 31CC9109B for ; Sat, 15 Aug 2020 06:32:38 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0A43B22D08 for ; 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bh=+xqa9UEJkEmmE6uCB5h1bOQifNwquSyXPo3G3a6IEMs=; b=HbC9t6u6ePlGy1Xl7JOLyFx5PUoziU1ilMgOC7fFM5iCjkOrtSAjFfpNJPuq2DNJKfleBaT4fMUyk9sj/SQoJqHwkKRi3J19j2RSnGrFM8tWH+lOF97SKefG/YhylrC9fUaSeTUYFI/HeM827seLFDcIuFGoMzchBVQK545Iiwg=; X-UUID: 32a23ffd1d6d41f99f759f7dfda6e6ce-20200814 Received: from mtkcas66.mediatek.inc [(172.29.193.44)] by mailgw01.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLS) with ESMTP id 1153257306; Fri, 14 Aug 2020 22:31:06 -0800 Received: from MTKMBS02N1.mediatek.inc (172.21.101.77) by MTKMBS62N2.mediatek.inc (172.29.193.42) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 14 Aug 2020 23:21:06 -0700 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs02n1.mediatek.inc (172.21.101.77) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sat, 15 Aug 2020 14:20:52 +0800 Received: from mtkswgap22.mediatek.inc (172.21.77.33) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Sat, 15 Aug 2020 14:20:54 +0800 From: Chinwen Chang To: Matthias Brugger , Michel Lespinasse , Andrew Morton , "Vlastimil Babka" , Daniel Jordan , "Davidlohr Bueso" , Chinwen Chang , "Alexey Dobriyan" , "Matthew Wilcox (Oracle)" , Jason Gunthorpe , Steven Price , Song Liu , Jimmy Assarsson , Huang Ying , Daniel Kiss , Laurent Dufour Subject: [PATCH v3 3/3] mm: proc: smaps_rollup: do not stall write attempts on mmap_lock Date: Sat, 15 Aug 2020 14:20:19 +0800 Message-ID: <1597472419-32314-4-git-send-email-chinwen.chang@mediatek.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1597472419-32314-1-git-send-email-chinwen.chang@mediatek.com> References: <1597472419-32314-1-git-send-email-chinwen.chang@mediatek.com> MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200815_023110_162803_865272DE X-CRM114-Status: GOOD ( 21.13 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.0 MIME_BASE64_TEXT RAW: Message text disguised using base64 encoding -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.0 UNPARSEABLE_RELAY Informational: message has unparseable relay lines X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-fsdevel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, wsd_upstream@mediatek.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org smaps_rollup will try to grab mmap_lock and go through the whole vma list until it finishes the iterating. When encountering large processes, the mmap_lock will be held for a longer time, which may block other write requests like mmap and munmap from progressing smoothly. There are upcoming mmap_lock optimizations like range-based locks, but the lock applied to smaps_rollup would be the coarse type, which doesn't avoid the occurrence of unpleasant contention. To solve aforementioned issue, we add a check which detects whether anyone wants to grab mmap_lock for write attempts. Change since v1: - If current VMA is freed after dropping the lock, it will return - incomplete result. To fix this issue, refine the code flow as - suggested by Steve. [1] Change since v2: - When getting back the mmap lock, the address where you stopped last - time could now be in the middle of a vma. Add one more check to handle - this case as suggested by Michel. [2] [1] https://lore.kernel.org/lkml/bf40676e-b14b-44cd-75ce-419c70194783@arm.com/ [2] https://lore.kernel.org/lkml/CANN689FtCsC71cjAjs0GPspOhgo_HRj+diWsoU1wr98YPktgWg@mail.gmail.com/ Signed-off-by: Chinwen Chang CC: Steven Price CC: Michel Lespinasse Reviewed-by: Steven Price --- fs/proc/task_mmu.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 70 insertions(+), 3 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 76e623a..945904e 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -846,7 +846,7 @@ static int show_smaps_rollup(struct seq_file *m, void *v) struct mem_size_stats mss; struct mm_struct *mm; struct vm_area_struct *vma; - unsigned long last_vma_end = 0; + unsigned long last_vma_end = 0, last_stopped = 0; int ret = 0; priv->task = get_proc_task(priv->inode); @@ -867,9 +867,76 @@ static int show_smaps_rollup(struct seq_file *m, void *v) hold_task_mempolicy(priv); - for (vma = priv->mm->mmap; vma; vma = vma->vm_next) { - smap_gather_stats(vma, &mss, 0); + for (vma = priv->mm->mmap; vma;) { + smap_gather_stats(vma, &mss, last_stopped); + last_stopped = 0; last_vma_end = vma->vm_end; + + /* + * Release mmap_lock temporarily if someone wants to + * access it for write request. + */ + if (mmap_lock_is_contended(mm)) { + mmap_read_unlock(mm); + ret = mmap_read_lock_killable(mm); + if (ret) { + release_task_mempolicy(priv); + goto out_put_mm; + } + + /* + * After dropping the lock, there are four cases to + * consider. See the following example for explanation. + * + * +------+------+-----------+ + * | VMA1 | VMA2 | VMA3 | + * +------+------+-----------+ + * | | | | + * 4k 8k 16k 400k + * + * Suppose we drop the lock after reading VMA2 due to + * contention, then we get: + * + * last_vma_end = 16k + * + * 1) VMA2 is freed, but VMA3 exists: + * + * find_vma(mm, 16k - 1) will return VMA3. + * In this case, just continue from VMA3. + * + * 2) VMA2 still exists: + * + * find_vma(mm, 16k - 1) will return VMA2. + * Iterate the loop like the original one. + * + * 3) No more VMAs can be found: + * + * find_vma(mm, 16k - 1) will return NULL. + * No more things to do, just break. + * + * 4) (last_vma_end - 1) is the middle of a vma (VMA'): + * + * find_vma(mm, 16k - 1) will return VMA' whose range + * contains last_vma_end. + * Iterate VMA' from last_vma_end. + */ + vma = find_vma(mm, last_vma_end - 1); + /* Case 3 above */ + if (!vma) + break; + + /* Case 1 above */ + if (vma->vm_start >= last_vma_end) + continue; + + /* Case 4 above */ + if (vma->vm_end > last_vma_end) { + last_stopped = last_vma_end; + continue; + } + } + /* Case 2 above */ + vma = vma->vm_next; } show_vma_header_prefix(m, priv->mm->mmap->vm_start,