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 X-Spam-Level: X-Spam-Status: No, score=-5.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MIME_BASE64_TEXT,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B96C7C433DF for ; Thu, 13 Aug 2020 02:13:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95D6C22BF5 for ; Thu, 13 Aug 2020 02:13:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b="lhd/2RrY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726658AbgHMCNv (ORCPT ); Wed, 12 Aug 2020 22:13:51 -0400 Received: from mailgw02.mediatek.com ([210.61.82.184]:48592 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726605AbgHMCNu (ORCPT ); Wed, 12 Aug 2020 22:13:50 -0400 X-UUID: dfad2300fe9a44c3b23ad3781c03596b-20200813 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:Content-Type:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=aF1D+BCyiRCtqB/9T1GyAsWkEq1ttG2TVqo5h3JEkxo=; b=lhd/2RrY8T0f6YKQIjm4brzBv6gAsEKFXZ5XX0tHceBMZOLPU0+mNhyrtBsWIxCc9HfwvRXRm3hOogf+C4nB6RInkLlfK3bYVsaFyv87lrTFFeMy30OU8Nugdgyhd/NvPD1pgLYQlfxJL9QvSYFkdrefIKPNBE8Q7SIb66tY8K4=; X-UUID: dfad2300fe9a44c3b23ad3781c03596b-20200813 Received: from mtkcas07.mediatek.inc [(172.21.101.84)] by mailgw02.mediatek.com (envelope-from ) (Cellopoint E-mail Firewall v4.1.10 Build 0809 with TLS) with ESMTP id 631092834; Thu, 13 Aug 2020 10:13:46 +0800 Received: from mtkcas08.mediatek.inc (172.21.101.126) by mtkmbs02n1.mediatek.inc (172.21.101.77) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 13 Aug 2020 10:13:45 +0800 Received: from mtkswgap22.mediatek.inc (172.21.77.33) by mtkcas08.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 13 Aug 2020 10:13:45 +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 CC: , , , , Subject: [PATCH v2 0/2] Try to release mmap_lock temporarily in smaps_rollup Date: Thu, 13 Aug 2020 10:13:28 +0800 Message-ID: <1597284810-17454-1-git-send-email-chinwen.chang@mediatek.com> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 Content-Type: text/plain X-MTK: N Content-Transfer-Encoding: base64 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org UmVjZW50bHksIHdlIGhhdmUgb2JzZXJ2ZWQgc29tZSBqYW5reSBpc3N1ZXMgY2F1c2VkIGJ5IHVu cGxlYXNhbnRseSBsb25nDQpjb250ZW50aW9uIG9uIG1tYXBfbG9jayB3aGljaCBpcyBoZWxkIGJ5 IHNtYXBzX3JvbGx1cCB3aGVuIHByb2JpbmcgbGFyZ2UNCnByb2Nlc3Nlcy4gVG8gYWRkcmVzcyB0 aGUgcHJvYmxlbSwgd2UgbGV0IHNtYXBzX3JvbGx1cCBkZXRlY3QgaWYgYW55b25lDQp3YW50cyB0 byBhY3F1aXJlIG1tYXBfbG9jayBmb3Igd3JpdGUgYXR0ZW1wdHMuIElmIHllcywganVzdCByZWxl YXNlIHRoZQ0KbG9jayB0ZW1wb3JhcmlseSB0byBlYXNlIHRoZSBjb250ZW50aW9uLg0KDQpzbWFw c19yb2xsdXAgaXMgYSBwcm9jZnMgaW50ZXJmYWNlIHdoaWNoIGFsbG93cyB1c2VycyB0byBzdW1t YXJpemUgdGhlDQpwcm9jZXNzJ3MgbWVtb3J5IHVzYWdlIHdpdGhvdXQgdGhlIG92ZXJoZWFkIG9m IHNlcV8qIGNhbGxzLiBBbmRyb2lkIHVzZXMgaXQNCnRvIHNhbXBsZSB0aGUgbWVtb3J5IHVzYWdl IG9mIHZhcmlvdXMgcHJvY2Vzc2VzIHRvIGJhbGFuY2UgaXRzIG1lbW9yeSBwb29sDQpzaXplcy4g SWYgbm8gb25lIHdhbnRzIHRvIHRha2UgdGhlIGxvY2sgZm9yIHdyaXRlIHJlcXVlc3RzLCBzbWFw c19yb2xsdXANCndpdGggdGhpcyBwYXRjaCB3aWxsIGJlaGF2ZSBsaWtlIHRoZSBvcmlnaW5hbCBv bmUuDQoNCkFsdGhvdWdoIHRoZXJlIGFyZSBvbi1nb2luZyBtbWFwX2xvY2sgb3B0aW1pemF0aW9u cyBsaWtlIHJhbmdlLWJhc2VkIGxvY2tzLA0KdGhlIGxvY2sgYXBwbGllZCB0byBzbWFwc19yb2xs dXAgd291bGQgYmUgdGhlIGNvYXJzZSBvbmUsIHdoaWNoIGlzIGhhcmQgdG8NCmF2b2lkIHRoZSBv Y2N1cnJlbmNlIG9mIGFmb3JlbWVudGlvbmVkIGlzc3Vlcy4gU28gdGhlIGRldGVjdGlvbiBhbmQN CnRlbXBvcmFyeSByZWxlYXNlIGZvciB3cml0ZSBhdHRlbXB0cyBvbiBtbWFwX2xvY2sgaW4gc21h cHNfcm9sbHVwIGlzIHN0aWxsDQpuZWNlc3NhcnkuDQoNCkNoYW5nZSBzaW5jZSB2MToNCi0gSWYg Y3VycmVudCBWTUEgaXMgZnJlZWQgYWZ0ZXIgZHJvcHBpbmcgdGhlIGxvY2ssIGl0IHdpbGwgcmV0 dXJuDQotIGluY29tcGxldGUgcmVzdWx0LiBUbyBmaXggdGhpcyBpc3N1ZSwgcmVmaW5lIHRoZSBj b2RlIGZsb3cgYXMNCi0gc3VnZ2VzdGVkIGJ5IFN0ZXZlLiBbMV0NCg0KWzFdIGh0dHBzOi8vbG9y ZS5rZXJuZWwub3JnL2xrbWwvYmY0MDY3NmUtYjE0Yi00NGNkLTc1Y2UtNDE5YzcwMTk0NzgzQGFy bS5jb20vDQoNCg0KQ2hpbndlbiBDaGFuZyAoMik6DQogIG1tYXAgbG9ja2luZyBBUEk6IGFkZCBt bWFwX2xvY2tfaXNfY29udGVuZGVkKCkNCiAgbW06IHByb2M6IHNtYXBzX3JvbGx1cDogZG8gbm90 IHN0YWxsIHdyaXRlIGF0dGVtcHRzIG9uIG1tYXBfbG9jaw0KDQogZnMvcHJvYy90YXNrX21tdS5j ICAgICAgICB8IDU3ICsrKysrKysrKysrKysrKysrKysrKysrKysrKysrKysrKysrKysrLQ0KIGlu Y2x1ZGUvbGludXgvbW1hcF9sb2NrLmggfCAgNSArKysrDQogMiBmaWxlcyBjaGFuZ2VkLCA2MSBp bnNlcnRpb25zKCspLCAxIGRlbGV0aW9uKC0p 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 X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6726C433E0 for ; Thu, 13 Aug 2020 02:14:13 +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 974D420771 for ; Thu, 13 Aug 2020 02:14:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Gw4aE07f"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b="iBEvIDhk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 974D420771 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:To:From: Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender :Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=In5BEDYzvM+LqxrUOzEdSlHh7ldZDgSoWPdZ9PK0U34=; b=Gw4aE07fj/osksd4xEdE7kFxCm DjPZ0oSEJMMTbQJtup/ZWSNWB+g0X5p9pn3x6j653Xg0uSEZ9/hBNzBAZIMRTCscHe8+jBmCJeRWn zD/TGkVsIgGQG2vB8zq20Xbk5QGRhlync3NRu3+KXxSafMQXAbvDnVZPVWYvseHBmwbI5aqmKBNcu cD4uoDeD5IondjlYpdhwOfkRzmzOOQLfeIL61f8kEYl/SH51ZAVFl21Yh+0YTDK/LJZ1UciSgZadb nI2M1wCPiXY4dMF1wxsXnaSgLdKTryLGnqRTkvBcJjLn1c9gYZtcMP3HFLpF0MWzgGyinDDliLh+d qC6seJgQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k62km-0003Tg-Hm; Thu, 13 Aug 2020 02:14:04 +0000 Received: from mailgw02.mediatek.com ([216.200.240.185]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k62ki-0003Rr-SA; Thu, 13 Aug 2020 02:14:02 +0000 X-UUID: 2794ca0de241451ab5f5e84cad1e9b1e-20200812 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:Content-Type:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=aF1D+BCyiRCtqB/9T1GyAsWkEq1ttG2TVqo5h3JEkxo=; b=iBEvIDhkcs6plnbJGYTJTybOT8PtjIeTJWVB6qEItJ5wE8T+KT5wBPVAWzbaoqOQmCDm+FEVaKHt7JEjukxum46gfzHUTT0rXnPGC/gSv+kHzXgyQ9vD3DmljqukS7O19IY74Yiow8WZbMRSbGn9x8cPgNtQ1TFsGe6uNU929WE=; X-UUID: 2794ca0de241451ab5f5e84cad1e9b1e-20200812 Received: from mtkcas66.mediatek.inc [(172.29.193.44)] by mailgw02.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLS) with ESMTP id 863826039; Wed, 12 Aug 2020 18:13:53 -0800 Received: from MTKMBS02N1.mediatek.inc (172.21.101.77) by MTKMBS62DR.mediatek.inc (172.29.94.18) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 12 Aug 2020 19:13:52 -0700 Received: from mtkcas08.mediatek.inc (172.21.101.126) by mtkmbs02n1.mediatek.inc (172.21.101.77) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 13 Aug 2020 10:13:45 +0800 Received: from mtkswgap22.mediatek.inc (172.21.77.33) by mtkcas08.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 13 Aug 2020 10:13:45 +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 Subject: [PATCH v2 0/2] Try to release mmap_lock temporarily in smaps_rollup Date: Thu, 13 Aug 2020 10:13:28 +0800 Message-ID: <1597284810-17454-1-git-send-email-chinwen.chang@mediatek.com> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200812_221401_058236_FD1C7D3A X-CRM114-Status: GOOD ( 13.86 ) X-BeenThere: linux-mediatek@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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org Recently, we have observed some janky issues caused by unpleasantly long contention on mmap_lock which is held by smaps_rollup when probing large processes. To address the problem, we let smaps_rollup detect if anyone wants to acquire mmap_lock for write attempts. If yes, just release the lock temporarily to ease the contention. smaps_rollup is a procfs interface which allows users to summarize the process's memory usage without the overhead of seq_* calls. Android uses it to sample the memory usage of various processes to balance its memory pool sizes. If no one wants to take the lock for write requests, smaps_rollup with this patch will behave like the original one. Although there are on-going mmap_lock optimizations like range-based locks, the lock applied to smaps_rollup would be the coarse one, which is hard to avoid the occurrence of aforementioned issues. So the detection and temporary release for write attempts on mmap_lock in smaps_rollup is still necessary. 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] [1] https://lore.kernel.org/lkml/bf40676e-b14b-44cd-75ce-419c70194783@arm.com/ Chinwen Chang (2): mmap locking API: add mmap_lock_is_contended() mm: proc: smaps_rollup: do not stall write attempts on mmap_lock fs/proc/task_mmu.c | 57 ++++++++++++++++++++++++++++++++++++++- include/linux/mmap_lock.h | 5 ++++ 2 files changed, 61 insertions(+), 1 deletion(-) _______________________________________________ Linux-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek 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 X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D171C433E0 for ; Thu, 13 Aug 2020 02:15:51 +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 44473206A4 for ; Thu, 13 Aug 2020 02:15:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="h7/se92r"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b="iBEvIDhk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 44473206A4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:To:From: Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender :Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=5KxoaExcZnswkKS00xWrM4NTNPCSpmz2aKEzpuTA67Q=; b=h7/se92rdHrFtycb/EhvogpbF/ 35VLQQeimvQBF+KxDLGQKIEXQr96jlylKXurA6/MW1XZ7ViMrkuDBoR8Na9/nc1qInJPwgnK5zII7 J8h9W3WxMv6nmX7g7Wzd8iEqFBz5Iue13e0rjLxhZVrYlZp0Q1H8dJwzjrTUFr1KWduUD6/ToJLhA 6OBoG0X+GZzt9hOjMJnvLbqOCqihIp5vZZ6U1y34mBDTiYtZ9vYI67qisd3ROjOvYV/cs+9TN+OLj dw2Idz7CDFHKQJHoMgAuJYvsQ/5qLj23OHXRBz4pvnzVzo91XQqZS22571ABDEE2ZS5DC3MuCkhbB +LEPXnjA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k62kk-0003TE-Sk; Thu, 13 Aug 2020 02:14:02 +0000 Received: from mailgw02.mediatek.com ([216.200.240.185]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k62ki-0003Rr-SA; Thu, 13 Aug 2020 02:14:02 +0000 X-UUID: 2794ca0de241451ab5f5e84cad1e9b1e-20200812 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:Content-Type:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=aF1D+BCyiRCtqB/9T1GyAsWkEq1ttG2TVqo5h3JEkxo=; b=iBEvIDhkcs6plnbJGYTJTybOT8PtjIeTJWVB6qEItJ5wE8T+KT5wBPVAWzbaoqOQmCDm+FEVaKHt7JEjukxum46gfzHUTT0rXnPGC/gSv+kHzXgyQ9vD3DmljqukS7O19IY74Yiow8WZbMRSbGn9x8cPgNtQ1TFsGe6uNU929WE=; X-UUID: 2794ca0de241451ab5f5e84cad1e9b1e-20200812 Received: from mtkcas66.mediatek.inc [(172.29.193.44)] by mailgw02.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLS) with ESMTP id 863826039; Wed, 12 Aug 2020 18:13:53 -0800 Received: from MTKMBS02N1.mediatek.inc (172.21.101.77) by MTKMBS62DR.mediatek.inc (172.29.94.18) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 12 Aug 2020 19:13:52 -0700 Received: from mtkcas08.mediatek.inc (172.21.101.126) by mtkmbs02n1.mediatek.inc (172.21.101.77) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 13 Aug 2020 10:13:45 +0800 Received: from mtkswgap22.mediatek.inc (172.21.77.33) by mtkcas08.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 13 Aug 2020 10:13:45 +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 Subject: [PATCH v2 0/2] Try to release mmap_lock temporarily in smaps_rollup Date: Thu, 13 Aug 2020 10:13:28 +0800 Message-ID: <1597284810-17454-1-git-send-email-chinwen.chang@mediatek.com> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200812_221401_058236_FD1C7D3A X-CRM114-Status: GOOD ( 13.86 ) 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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Recently, we have observed some janky issues caused by unpleasantly long contention on mmap_lock which is held by smaps_rollup when probing large processes. To address the problem, we let smaps_rollup detect if anyone wants to acquire mmap_lock for write attempts. If yes, just release the lock temporarily to ease the contention. smaps_rollup is a procfs interface which allows users to summarize the process's memory usage without the overhead of seq_* calls. Android uses it to sample the memory usage of various processes to balance its memory pool sizes. If no one wants to take the lock for write requests, smaps_rollup with this patch will behave like the original one. Although there are on-going mmap_lock optimizations like range-based locks, the lock applied to smaps_rollup would be the coarse one, which is hard to avoid the occurrence of aforementioned issues. So the detection and temporary release for write attempts on mmap_lock in smaps_rollup is still necessary. 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] [1] https://lore.kernel.org/lkml/bf40676e-b14b-44cd-75ce-419c70194783@arm.com/ Chinwen Chang (2): mmap locking API: add mmap_lock_is_contended() mm: proc: smaps_rollup: do not stall write attempts on mmap_lock fs/proc/task_mmu.c | 57 ++++++++++++++++++++++++++++++++++++++- include/linux/mmap_lock.h | 5 ++++ 2 files changed, 61 insertions(+), 1 deletion(-) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel