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=-5.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLACK,URIBL_BLOCKED autolearn=ham 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 0A4A2C433E0 for ; Tue, 23 Jun 2020 16:56:04 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 CC3602076E for ; Tue, 23 Jun 2020 16:56:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=lca.pw header.i=@lca.pw header.b="q5PXizvo" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CC3602076E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lca.pw Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=amd-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6D5B86EA0C; Tue, 23 Jun 2020 16:56:03 +0000 (UTC) Received: from mail-qt1-x844.google.com (mail-qt1-x844.google.com [IPv6:2607:f8b0:4864:20::844]) by gabe.freedesktop.org (Postfix) with ESMTPS id 125CD6E9FC for ; Tue, 23 Jun 2020 16:18:02 +0000 (UTC) Received: by mail-qt1-x844.google.com with SMTP id h23so8702846qtr.0 for ; Tue, 23 Jun 2020 09:18:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lca.pw; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=SowX6r/DrbyMyIPo7bbmN6dCO4WOaZBpx8lXkNiYwRQ=; b=q5PXizvouRcfNA2W9Djqc/Z84L8gq+5xyPGe7rkAVVUXYo0XRUHAEI4yVuKgTSfgc9 RoYCG4UkEgCC9vVO+IYyrz7JORXpNUWmlzMkIni2Vfw9kxBsp2K+YgamdfZElTJuJZTW bbafUUDUQEhd51JcrBKUA9xHz8S+ZvnGFC/bx4j/zd/tIY4JT4nqabnA6jtnfro4Yx69 YevfddRvEKhgwHMyV0hQh6x3L1BXH3reCRQkEUr6zmcuCWOBikrw37RohUhW9xkrCqv7 nLIezDVzEaNlXEnFqrM5wDtOVHCyOyKL9todYtNNNUOatrNgrkdDPEXpNyPANNjAfT9T s5yg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=SowX6r/DrbyMyIPo7bbmN6dCO4WOaZBpx8lXkNiYwRQ=; b=X5aG9Y9z2mwyhu9f6kkn+Wqp5g/IA8gL1xaGyyNWJ5fTFRLvyLK6cP85XOaU86esDc L8BWXJs2Ejigf6XDOD1LarzcWZ3jDX28q9njww6yGFjUN/S5Uq2ZN8ua3hWL4VjnevSq awj9DK4COhpAQ9kvqUJwHrkRLWc3YTmERFtXHbQx39TOytKr98dImLZyuAaWgr/rgm4K ME77D9xFuIQUw4l6iTjkbN/3k0BkZT5bZ9Iccbv5PYOh+BEzkm/sBrk4GvCGIYdjP/hw HQK6F1shAh2DfR8CJYZMjOzvqHIclM8w2uBvK7nK1IlDm2tB+x0YFLS8i6jn96/fJtTD NT2w== X-Gm-Message-State: AOAM5308mwrj7e14rcYv0lMvvWRV0JMf8h0MoX9X7t9dNc6NVSPJhEzn J8BEsfyGktIao/47PVhxDJ+viMXqvxWw5A== X-Google-Smtp-Source: ABdhPJy2/MUFYS3DJu96XPGFYPvGEfp9/cvT3JQEnV1SM172gUGWrPZ+0/Xawft3xZIbg4oUrttvEg== X-Received: by 2002:ac8:4448:: with SMTP id m8mr22935603qtn.4.1592929081912; Tue, 23 Jun 2020 09:18:01 -0700 (PDT) Received: from lca.pw (pool-71-184-117-43.bstnma.fios.verizon.net. [71.184.117.43]) by smtp.gmail.com with ESMTPSA id d140sm966654qkc.22.2020.06.23.09.18.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Jun 2020 09:18:01 -0700 (PDT) Date: Tue, 23 Jun 2020 12:17:54 -0400 From: Qian Cai To: Daniel Vetter Subject: Re: [PATCH] mm: Track mmu notifiers in fs_reclaim_acquire/release Message-ID: <20200623161754.GA1140@lca.pw> References: <20200604081224.863494-2-daniel.vetter@ffwll.ch> <20200610194101.1668038-1-daniel.vetter@ffwll.ch> <20200621174205.GB1398@lca.pw> <20200621200103.GV20149@phenom.ffwll.local> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200621200103.GV20149@phenom.ffwll.local> X-Mailman-Approved-At: Tue, 23 Jun 2020 16:56:01 +0000 X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-rdma , Intel Graphics Development , Maarten Lankhorst , LKML , amd-gfx list , Christian =?iso-8859-1?Q?K=F6nig?= , linux-xfs@vger.kernel.org, Linux MM , Jason Gunthorpe , DRI Development , Daniel Vetter , Andrew Morton , Thomas =?iso-8859-1?Q?Hellstr=F6m?= Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" On Sun, Jun 21, 2020 at 10:01:03PM +0200, Daniel Vetter wrote: > On Sun, Jun 21, 2020 at 08:07:08PM +0200, Daniel Vetter wrote: > > On Sun, Jun 21, 2020 at 7:42 PM Qian Cai wrote: > > > > > > On Wed, Jun 10, 2020 at 09:41:01PM +0200, Daniel Vetter wrote: > > > > fs_reclaim_acquire/release nicely catch recursion issues when > > > > allocating GFP_KERNEL memory against shrinkers (which gpu drivers t= end > > > > to use to keep the excessive caches in check). For mmu notifier > > > > recursions we do have lockdep annotations since 23b68395c7c7 > > > > ("mm/mmu_notifiers: add a lockdep map for invalidate_range_start/en= d"). > > > > > > > > But these only fire if a path actually results in some pte > > > > invalidation - for most small allocations that's very rarely the ca= se. > > > > The other trouble is that pte invalidation can happen any time when > > > > __GFP_RECLAIM is set. Which means only really GFP_ATOMIC is a safe > > > > choice, GFP_NOIO isn't good enough to avoid potential mmu notifier > > > > recursion. > > > > > > > > I was pondering whether we should just do the general annotation, b= ut > > > > there's always the risk for false positives. Plus I'm assuming that > > > > the core fs and io code is a lot better reviewed and tested than > > > > random mmu notifier code in drivers. Hence why I decide to only > > > > annotate for that specific case. > > > > > > > > Furthermore even if we'd create a lockdep map for direct reclaim, w= e'd > > > > still need to explicit pull in the mmu notifier map - there's a lot > > > > more places that do pte invalidation than just direct reclaim, these > > > > two contexts arent the same. > > > > > > > > Note that the mmu notifiers needing their own independent lockdep m= ap > > > > is also the reason we can't hold them from fs_reclaim_acquire to > > > > fs_reclaim_release - it would nest with the acquistion in the pte > > > > invalidation code, causing a lockdep splat. And we can't remove the > > > > annotations from pte invalidation and all the other places since > > > > they're called from many other places than page reclaim. Hence we c= an > > > > only do the equivalent of might_lock, but on the raw lockdep map. > > > > > > > > With this we can also remove the lockdep priming added in 66204f1d2= d1b > > > > ("mm/mmu_notifiers: prime lockdep") since the new annotations are > > > > strictly more powerful. > > > > > > > > v2: Review from Thomas Hellstrom: > > > > - unbotch the fs_reclaim context check, I accidentally inverted it, > > > > but it didn't blow up because I inverted it immediately > > > > - fix compiling for !CONFIG_MMU_NOTIFIER > > > > > > > > Cc: Thomas Hellstr=F6m (Intel) > > > > Cc: Andrew Morton > > > > Cc: Jason Gunthorpe > > > > Cc: linux-mm@kvack.org > > > > Cc: linux-rdma@vger.kernel.org > > > > Cc: Maarten Lankhorst > > > > Cc: Christian K=F6nig > > > > Signed-off-by: Daniel Vetter > > > > > > Replying the right patch here... > > > > > > Reverting this commit [1] fixed the lockdep warning below while apply= ing > > > some memory pressure. > > > > > > [1] linux-next cbf7c9d86d75 ("mm: track mmu notifiers in fs_reclaim_a= cquire/release") > > = > > Hm, then I'm confused because > > - there's not mmut notifier lockdep map in the splat at a.. > > - the patch is supposed to not change anything for fs_reclaim (but the > > interim version got that wrong) > > - looking at the paths it's kmalloc vs kswapd, both places I totally > > expect fs_reflaim to be used. > > = > > But you're claiming reverting this prevents the lockdep splat. If > > that's right, then my reasoning above is broken somewhere. Someone > > less blind than me having an idea? > > = > > Aside this is the first email I've typed, until I realized the first > > report was against the broken patch and that looked like a much more > > reasonable explanation (but didn't quite match up with the code > > paths). > = > Below diff should undo the functional change in my patch. Can you pls test > whether the lockdep splat is really gone with that? Might need a lot of > testing and memory pressure to be sure, since all these reclaim paths > aren't very deterministic. No, this patch does not help but reverting the whole patch still fixed the splat. > -Daniel > = > --- > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d807587c9ae6..27ea763c6155 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -4191,11 +4191,6 @@ void fs_reclaim_acquire(gfp_t gfp_mask) > if (gfp_mask & __GFP_FS) > __fs_reclaim_acquire(); > = > -#ifdef CONFIG_MMU_NOTIFIER > - lock_map_acquire(&__mmu_notifier_invalidate_range_start_map); > - lock_map_release(&__mmu_notifier_invalidate_range_start_map); > -#endif > - > } > } > EXPORT_SYMBOL_GPL(fs_reclaim_acquire); > -- = > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx