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Fri, 14 Aug 2020 17:08:00 +0800 Message-ID: <1597396082.32469.58.camel@mtkswgap22> Subject: Re: [PATCH v2 2/2] mm: proc: smaps_rollup: do not stall write attempts on mmap_lock From: Chinwen Chang To: Michel Lespinasse CC: Matthias Brugger , Andrew Morton , Vlastimil Babka , "Daniel Jordan" , Davidlohr Bueso , Alexey Dobriyan , "Matthew Wilcox (Oracle)" , Jason Gunthorpe , Steven Price , Song Liu , Jimmy Assarsson , Huang Ying , LKML , , , , Date: Fri, 14 Aug 2020 17:08:02 +0800 In-Reply-To: References: <1597284810-17454-1-git-send-email-chinwen.chang@mediatek.com> <1597284810-17454-3-git-send-email-chinwen.chang@mediatek.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 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 T24gRnJpLCAyMDIwLTA4LTE0IGF0IDAxOjM1IC0wNzAwLCBNaWNoZWwgTGVzcGluYXNzZSB3cm90 ZToNCj4gT24gV2VkLCBBdWcgMTIsIDIwMjAgYXQgNzoxMyBQTSBDaGlud2VuIENoYW5nDQo+IDxj aGlud2VuLmNoYW5nQG1lZGlhdGVrLmNvbT4gd3JvdGU6DQo+ID4gc21hcHNfcm9sbHVwIHdpbGwg dHJ5IHRvIGdyYWIgbW1hcF9sb2NrIGFuZCBnbyB0aHJvdWdoIHRoZSB3aG9sZSB2bWENCj4gPiBs aXN0IHVudGlsIGl0IGZpbmlzaGVzIHRoZSBpdGVyYXRpbmcuIFdoZW4gZW5jb3VudGVyaW5nIGxh cmdlIHByb2Nlc3NlcywNCj4gPiB0aGUgbW1hcF9sb2NrIHdpbGwgYmUgaGVsZCBmb3IgYSBsb25n ZXIgdGltZSwgd2hpY2ggbWF5IGJsb2NrIG90aGVyDQo+ID4gd3JpdGUgcmVxdWVzdHMgbGlrZSBt bWFwIGFuZCBtdW5tYXAgZnJvbSBwcm9ncmVzc2luZyBzbW9vdGhseS4NCj4gPg0KPiA+IFRoZXJl IGFyZSB1cGNvbWluZyBtbWFwX2xvY2sgb3B0aW1pemF0aW9ucyBsaWtlIHJhbmdlLWJhc2VkIGxv Y2tzLCBidXQNCj4gPiB0aGUgbG9jayBhcHBsaWVkIHRvIHNtYXBzX3JvbGx1cCB3b3VsZCBiZSB0 aGUgY29hcnNlIHR5cGUsIHdoaWNoIGRvZXNuJ3QNCj4gPiBhdm9pZCB0aGUgb2NjdXJyZW5jZSBv ZiB1bnBsZWFzYW50IGNvbnRlbnRpb24uDQo+ID4NCj4gPiBUbyBzb2x2ZSBhZm9yZW1lbnRpb25l ZCBpc3N1ZSwgd2UgYWRkIGEgY2hlY2sgd2hpY2ggZGV0ZWN0cyB3aGV0aGVyDQo+ID4gYW55b25l IHdhbnRzIHRvIGdyYWIgbW1hcF9sb2NrIGZvciB3cml0ZSBhdHRlbXB0cy4NCj4gDQo+IEkgdGhp bmsgeW91ciByZXRyeSBtZWNoYW5pc20gc3RpbGwgZG9lc24ndCBoYW5kbGUgYWxsIGNhc2VzLiBX aGVuIHlvdQ0KPiBnZXQgYmFjayB0aGUgbW1hcCBsb2NrLCB0aGUgYWRkcmVzcyB3aGVyZSB5b3Ug c3RvcHBlZCBsYXN0IHRpbWUgY291bGQNCj4gbm93IGJlIGluIHRoZSBtaWRkbGUgb2YgYSB2bWEu IEkgdGhpbmsgdGhlIGNvbnNpc3RlbnQgdGhpbmcgdG8gZG8gaW4NCj4gdGhhdCBjYXNlIHdvdWxk IGJlIHRvIHJldHJ5IHNjYW5uaW5nIGZyb20gdGhlIGFkZHJlc3MgeW91IHN0b3BwZWQgYXQsDQo+ IGV2ZW4gaWYgaXQncyBub3Qgb24gYSB2bWEgYm91bmRhcnkgYW55bW9yZS4gWW91IG1heSBoYXZl IHRvIGNoYW5nZQ0KPiBzbWFwX2dhdGhlcl9zdGF0cyB0byBzdXBwb3J0IHRoYXQsIHRob3VnaC4N Cg0KSGkgTWljaGVsLA0KDQpJIHRoaW5rIEkgZ290IHlvdXIgcG9pbnQuIExldCBtZSB0cnkgdG8g cHJlcGFyZSBuZXcgcGF0Y2ggc2VyaWVzIGZvcg0KZnVydGhlciByZXZpZXdzLg0KDQpUaGFuayB5 b3UgZm9yIHlvdXIgc3VnZ2VzdGlvbiA6KQ0KDQpDaGlud2VuDQo= 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=-5.5 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,URIBL_BLOCKED,USER_AGENT_SANE_2 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 DC90AC433DF for ; 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Fri, 14 Aug 2020 09:08:11 +0000 X-UUID: d598d854ce104cdb96b8ec073e94ee7b-20200814 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:MIME-Version:Content-Type:References:In-Reply-To:Date:CC:To:From:Subject:Message-ID; bh=Uz5ripoV/+pUZcgYYnjGHaVEtX3lTJMQY1UuM8dECro=; b=Q8Iy3+0igqsaru66x1pWQmfZx9rUW7611iexjivvXFooJMbrTk3BQMjSjxdaCp9sa3iuGruzoE+EpKygf0EZKk57lUvp/J9bSEBrA44AGiy7SPlOqfYCQP5OH1UEVLmdCSfC1TwgIYU1JJd5uxRC0rASv4HquAIJrsuXkPUi5x8=; X-UUID: d598d854ce104cdb96b8ec073e94ee7b-20200814 Received: from mtkcas67.mediatek.inc [(172.29.193.45)] by mailgw01.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLS) with ESMTP id 231710915; Fri, 14 Aug 2020 01:08:04 -0800 Received: from MTKMBS01N1.mediatek.inc (172.21.101.68) by MTKMBS62N2.mediatek.inc (172.29.193.42) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 14 Aug 2020 02:08:05 -0700 Received: from MTKCAS06.mediatek.inc (172.21.101.30) by mtkmbs01n1.mediatek.inc (172.21.101.68) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 14 Aug 2020 17:08:00 +0800 Received: from [172.21.77.33] (172.21.77.33) by MTKCAS06.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Fri, 14 Aug 2020 17:08:00 +0800 Message-ID: <1597396082.32469.58.camel@mtkswgap22> Subject: Re: [PATCH v2 2/2] mm: proc: smaps_rollup: do not stall write attempts on mmap_lock From: Chinwen Chang To: Michel Lespinasse Date: Fri, 14 Aug 2020 17:08:02 +0800 In-Reply-To: References: <1597284810-17454-1-git-send-email-chinwen.chang@mediatek.com> <1597284810-17454-3-git-send-email-chinwen.chang@mediatek.com> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200814_050809_996120_B01C4F96 X-CRM114-Status: GOOD ( 19.83 ) 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-arm-kernel@lists.infradead.org, Song Liu , wsd_upstream@mediatek.com, Davidlohr Bueso , LKML , "Matthew Wilcox \(Oracle\)" , Daniel Jordan , Jason Gunthorpe , linux-mediatek@lists.infradead.org, Jimmy Assarsson , Huang Ying , Matthias Brugger , linux-fsdevel@vger.kernel.org, Andrew Morton , Steven Price , Alexey Dobriyan , Vlastimil Babka 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 On Fri, 2020-08-14 at 01:35 -0700, Michel Lespinasse wrote: > On Wed, Aug 12, 2020 at 7:13 PM Chinwen Chang > wrote: > > 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. > > I think your retry mechanism still doesn't handle all cases. When you > get back the mmap lock, the address where you stopped last time could > now be in the middle of a vma. I think the consistent thing to do in > that case would be to retry scanning from the address you stopped at, > even if it's not on a vma boundary anymore. You may have to change > smap_gather_stats to support that, though. Hi Michel, I think I got your point. Let me try to prepare new patch series for further reviews. Thank you for your suggestion :) Chinwen _______________________________________________ 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=-5.5 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,URIBL_BLOCKED,USER_AGENT_SANE_2 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 ED343C433E1 for ; Fri, 14 Aug 2020 09:09:38 +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 B289D207DA for ; 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bh=Uz5ripoV/+pUZcgYYnjGHaVEtX3lTJMQY1UuM8dECro=; b=Q8Iy3+0igqsaru66x1pWQmfZx9rUW7611iexjivvXFooJMbrTk3BQMjSjxdaCp9sa3iuGruzoE+EpKygf0EZKk57lUvp/J9bSEBrA44AGiy7SPlOqfYCQP5OH1UEVLmdCSfC1TwgIYU1JJd5uxRC0rASv4HquAIJrsuXkPUi5x8=; X-UUID: d598d854ce104cdb96b8ec073e94ee7b-20200814 Received: from mtkcas67.mediatek.inc [(172.29.193.45)] by mailgw01.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLS) with ESMTP id 231710915; Fri, 14 Aug 2020 01:08:04 -0800 Received: from MTKMBS01N1.mediatek.inc (172.21.101.68) by MTKMBS62N2.mediatek.inc (172.29.193.42) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 14 Aug 2020 02:08:05 -0700 Received: from MTKCAS06.mediatek.inc (172.21.101.30) by mtkmbs01n1.mediatek.inc (172.21.101.68) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 14 Aug 2020 17:08:00 +0800 Received: from [172.21.77.33] (172.21.77.33) by MTKCAS06.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Fri, 14 Aug 2020 17:08:00 +0800 Message-ID: <1597396082.32469.58.camel@mtkswgap22> Subject: Re: [PATCH v2 2/2] mm: proc: smaps_rollup: do not stall write attempts on mmap_lock From: Chinwen Chang To: Michel Lespinasse Date: Fri, 14 Aug 2020 17:08:02 +0800 In-Reply-To: References: <1597284810-17454-1-git-send-email-chinwen.chang@mediatek.com> <1597284810-17454-3-git-send-email-chinwen.chang@mediatek.com> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200814_050809_996120_B01C4F96 X-CRM114-Status: GOOD ( 19.83 ) 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-arm-kernel@lists.infradead.org, Song Liu , wsd_upstream@mediatek.com, Davidlohr Bueso , LKML , "Matthew Wilcox \(Oracle\)" , Daniel Jordan , Jason Gunthorpe , linux-mediatek@lists.infradead.org, Jimmy Assarsson , Huang Ying , Matthias Brugger , linux-fsdevel@vger.kernel.org, Andrew Morton , Steven Price , Alexey Dobriyan , Vlastimil Babka 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 On Fri, 2020-08-14 at 01:35 -0700, Michel Lespinasse wrote: > On Wed, Aug 12, 2020 at 7:13 PM Chinwen Chang > wrote: > > 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. > > I think your retry mechanism still doesn't handle all cases. When you > get back the mmap lock, the address where you stopped last time could > now be in the middle of a vma. I think the consistent thing to do in > that case would be to retry scanning from the address you stopped at, > even if it's not on a vma boundary anymore. You may have to change > smap_gather_stats to support that, though. Hi Michel, I think I got your point. Let me try to prepare new patch series for further reviews. Thank you for your suggestion :) Chinwen _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel