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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLACK autolearn=unavailable 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 DD774C433E4 for ; Sun, 21 Jun 2020 17:28:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE0AF25214 for ; Sun, 21 Jun 2020 17:28:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="WvK+FioI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730467AbgFUR2y (ORCPT ); Sun, 21 Jun 2020 13:28:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60550 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730452AbgFUR2y (ORCPT ); Sun, 21 Jun 2020 13:28:54 -0400 Received: from mail-ot1-x341.google.com (mail-ot1-x341.google.com [IPv6:2607:f8b0:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B5CB4C061794 for ; Sun, 21 Jun 2020 10:28:52 -0700 (PDT) Received: by mail-ot1-x341.google.com with SMTP id v13so11264668otp.4 for ; Sun, 21 Jun 2020 10:28:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=vNRv7uHgjha7M7aHwPnuElgho0c629S8DHnSxwFDyc8=; b=WvK+FioI/lKnxuQS44XN65z6bePEwHIpUwxSwkzF+UtORJOQIHuwMffbBwpPXshD8p TPqU56QJFulx9ltBruI2OOUAa4YO97Hgx7Wm6KYy68FDYH4Ze+Kbs71KP5uwJThbgAdJ 2Vaz9O3iRdVrhQy++CsUf724zEXHXOqv5Bmhg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=vNRv7uHgjha7M7aHwPnuElgho0c629S8DHnSxwFDyc8=; b=t6LlGS9vmeyjKnuaPnUD8bQ+CbhLLZtVy/2Dt7B+X455ZFqVWf+d5JiqDOSZ7rWQJ/ VFShYFFvqJWNDk4mn6cqVW1CAhL0F1cmBrTKJn5wt8g3GgYEMKmkGJs4hqhrRqs6NsKD np8h2bV2085zyBS+kpFr/SA+EFw0dpqG0TLubKQQ65bNciIgtiBvw5T8uyXqV20nKM5r JH/xfLFP0XIbTB+mmn8Si69QMS2EXmHwpAH1KLHFFDmZcLa9N6MFk7vtpdbcNGnwh+WG zkM/EYwbfHD1PIRMZb3l2nyUX87kvU37puY5UwsnhQmo46XFLsdpW7gf/47Sgc8yKXmO ohiw== X-Gm-Message-State: AOAM533GvaMmrOV0bOy3v9EE/fioVkqpxF1JZYQOAR3Vs6IHtfJeBNyU RPq5H308juRzQuiBw8KVXLvmjzq/Y2fp0so7143ROg== X-Google-Smtp-Source: ABdhPJyNh+7DVQF7BJqd3ZQEmmHZN9vTj22EV5HLeg9Svdz3f9iQ0lGHyQxB/CDALFlyWj1+Og3U8SNHSKQb1uauAkw= X-Received: by 2002:a05:6830:2017:: with SMTP id e23mr3965686otp.303.1592760531870; Sun, 21 Jun 2020 10:28:51 -0700 (PDT) MIME-Version: 1.0 References: <20200604081224.863494-1-daniel.vetter@ffwll.ch> <20200604081224.863494-2-daniel.vetter@ffwll.ch> <20200621170054.GA1398@lca.pw> In-Reply-To: <20200621170054.GA1398@lca.pw> From: Daniel Vetter Date: Sun, 21 Jun 2020 19:28:40 +0200 Message-ID: Subject: Re: [PATCH 01/18] mm: Track mmu notifiers in fs_reclaim_acquire/release To: Qian Cai Cc: DRI Development , Intel Graphics Development , LKML , linux-rdma , amd-gfx list , Andrew Morton , Jason Gunthorpe , Linux MM , Maarten Lankhorst , =?UTF-8?Q?Christian_K=C3=B6nig?= , Daniel Vetter , linux-xfs@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Sun, Jun 21, 2020 at 7:01 PM Qian Cai wrote: > > On Thu, Jun 04, 2020 at 10:12:07AM +0200, Daniel Vetter wrote: > > fs_reclaim_acquire/release nicely catch recursion issues when > > allocating GFP_KERNEL memory against shrinkers (which gpu drivers tend > > 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/end"). > > > > But these only fire if a path actually results in some pte > > invalidation - for most small allocations that's very rarely the case. > > 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, but > > 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, we'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 map > > 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 can > > only do the equivalent of might_lock, but on the raw lockdep map. > > > > With this we can also remove the lockdep priming added in 66204f1d2d1b > > ("mm/mmu_notifiers: prime lockdep") since the new annotations are > > strictly more powerful. > > > > Cc: Andrew Morton > > Cc: Jason Gunthorpe > > Cc: linux-mm@kvack.org > > Cc: linux-rdma@vger.kernel.org > > Cc: Maarten Lankhorst > > Cc: Christian K=C3=B6nig > > Signed-off-by: Daniel Vetter > > Reverting this commit fixed the lockdep splat below while applying some > memory pressure, This is a broken version of the patch, please use the one Andrew merged into -mm. Thanks, Daniel > > [ 190.455003][ T369] WARNING: possible circular locking dependency dete= cted > [ 190.487291][ T369] 5.8.0-rc1-next-20200621 #1 Not tainted > [ 190.512363][ T369] --------------------------------------------------= ---- > [ 190.543354][ T369] kswapd3/369 is trying to acquire lock: > [ 190.568523][ T369] ffff889fcf694528 (&xfs_nondir_ilock_class){++++}-{= 3:3}, at: xfs_reclaim_inode+0xdf/0x860 > spin_lock at include/linux/spinlock.h:353 > (inlined by) xfs_iflags_test_and_set at fs/xfs/xfs_inode.h:166 > (inlined by) xfs_iflock_nowait at fs/xfs/xfs_inode.h:249 > (inlined by) xfs_reclaim_inode at fs/xfs/xfs_icache.c:1127 > [ 190.614359][ T369] > [ 190.614359][ T369] but task is already holding lock: > [ 190.647763][ T369] ffffffffb50ced00 (fs_reclaim){+.+.}-{0:0}, at: __f= s_reclaim_acquire+0x0/0x30 > __fs_reclaim_acquire at mm/page_alloc.c:4200 > [ 190.687845][ T369] > [ 190.687845][ T369] which lock already depends on the new lock. > [ 190.687845][ T369] > [ 190.734890][ T369] > [ 190.734890][ T369] the existing dependency chain (in reverse order) i= s: > [ 190.775991][ T369] > [ 190.775991][ T369] -> #1 (fs_reclaim){+.+.}-{0:0}: > [ 190.808150][ T369] fs_reclaim_acquire+0x77/0x80 > [ 190.832152][ T369] slab_pre_alloc_hook.constprop.52+0x20/0x120 > slab_pre_alloc_hook at mm/slab.h:507 > [ 190.862173][ T369] kmem_cache_alloc+0x43/0x2a0 > [ 190.885602][ T369] kmem_zone_alloc+0x113/0x3ef > kmem_zone_alloc at fs/xfs/kmem.c:129 > [ 190.908702][ T369] xfs_inode_item_init+0x1d/0xa0 > xfs_inode_item_init at fs/xfs/xfs_inode_item.c:639 > [ 190.934461][ T369] xfs_trans_ijoin+0x96/0x100 > xfs_trans_ijoin at fs/xfs/libxfs/xfs_trans_inode.c:34 > [ 190.961530][ T369] xfs_setattr_nonsize+0x1a6/0xcd0 > xfs_setattr_nonsize at fs/xfs/xfs_iops.c:716 > [ 190.987331][ T369] xfs_vn_setattr+0x133/0x160 > xfs_vn_setattr at fs/xfs/xfs_iops.c:1081 > [ 191.010476][ T369] notify_change+0x6c5/0xba1 > notify_change at fs/attr.c:336 > [ 191.033317][ T369] chmod_common+0x19b/0x390 > [ 191.055770][ T369] ksys_fchmod+0x28/0x60 > [ 191.077957][ T369] __x64_sys_fchmod+0x4e/0x70 > [ 191.102767][ T369] do_syscall_64+0x5f/0x310 > [ 191.125090][ T369] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [ 191.153749][ T369] > [ 191.153749][ T369] -> #0 (&xfs_nondir_ilock_class){++++}-{3:3}: > [ 191.191267][ T369] __lock_acquire+0x2efc/0x4da0 > [ 191.215974][ T369] lock_acquire+0x1ac/0xaf0 > [ 191.238953][ T369] down_write_nested+0x92/0x150 > [ 191.262955][ T369] xfs_reclaim_inode+0xdf/0x860 > [ 191.287149][ T369] xfs_reclaim_inodes_ag+0x505/0xb00 > [ 191.313291][ T369] xfs_reclaim_inodes_nr+0x93/0xd0 > [ 191.338357][ T369] super_cache_scan+0x2fd/0x430 > [ 191.362354][ T369] do_shrink_slab+0x317/0x990 > [ 191.385341][ T369] shrink_slab+0x3a8/0x4b0 > [ 191.407214][ T369] shrink_node+0x49c/0x17b0 > [ 191.429841][ T369] balance_pgdat+0x59c/0xed0 > [ 191.455041][ T369] kswapd+0x5a4/0xc40 > [ 191.477524][ T369] kthread+0x358/0x420 > [ 191.499285][ T369] ret_from_fork+0x22/0x30 > [ 191.521107][ T369] > [ 191.521107][ T369] other info that might help us debug this: > [ 191.521107][ T369] > [ 191.567490][ T369] Possible unsafe locking scenario: > [ 191.567490][ T369] > [ 191.600947][ T369] CPU0 CPU1 > [ 191.624808][ T369] ---- ---- > [ 191.649236][ T369] lock(fs_reclaim); > [ 191.667607][ T369] lock(&xfs_nondir_il= ock_class); > [ 191.702096][ T369] lock(fs_reclaim); > [ 191.731243][ T369] lock(&xfs_nondir_ilock_class); > [ 191.754025][ T369] > [ 191.754025][ T369] *** DEADLOCK *** > [ 191.754025][ T369] > [ 191.791126][ T369] 4 locks held by kswapd3/369: > [ 191.812198][ T369] #0: ffffffffb50ced00 (fs_reclaim){+.+.}-{0:0}, at= : __fs_reclaim_acquire+0x0/0x30 > [ 191.854319][ T369] #1: ffffffffb5074c50 (shrinker_rwsem){++++}-{3:3}= , at: shrink_slab+0x219/0x4b0 > [ 191.896043][ T369] #2: ffff8890279b40e0 (&type->s_umount_key#27){+++= +}-{3:3}, at: trylock_super+0x11/0xb0 > [ 191.940538][ T369] #3: ffff889027a73a28 (&pag->pag_ici_reclaim_lock)= {+.+.}-{3:3}, at: xfs_reclaim_inodes_ag+0x135/0xb00 > [ 191.995314][ T369] > [ 191.995314][ T369] stack backtrace: > [ 192.022934][ T369] CPU: 42 PID: 369 Comm: kswapd3 Not tainted 5.8.0-r= c1-next-20200621 #1 > [ 192.060546][ T369] Hardware name: HP ProLiant BL660c Gen9, BIOS I38 1= 0/17/2018 > [ 192.094518][ T369] Call Trace: > [ 192.109005][ T369] dump_stack+0x9d/0xe0 > [ 192.127468][ T369] check_noncircular+0x347/0x400 > [ 192.149526][ T369] ? print_circular_bug+0x360/0x360 > [ 192.172584][ T369] ? freezing_slow_path.cold.2+0x2a/0x2a > [ 192.197251][ T369] __lock_acquire+0x2efc/0x4da0 > [ 192.218737][ T369] ? lockdep_hardirqs_on_prepare+0x550/0x550 > [ 192.246736][ T369] ? __lock_acquire+0x3541/0x4da0 > [ 192.269673][ T369] lock_acquire+0x1ac/0xaf0 > [ 192.290192][ T369] ? xfs_reclaim_inode+0xdf/0x860 > [ 192.313158][ T369] ? rcu_read_unlock+0x50/0x50 > [ 192.335057][ T369] down_write_nested+0x92/0x150 > [ 192.358409][ T369] ? xfs_reclaim_inode+0xdf/0x860 > [ 192.380890][ T369] ? rwsem_down_write_slowpath+0xf50/0xf50 > [ 192.406891][ T369] ? find_held_lock+0x33/0x1c0 > [ 192.427925][ T369] ? xfs_ilock+0x2ef/0x370 > [ 192.447496][ T369] ? xfs_reclaim_inode+0xdf/0x860 > [ 192.472315][ T369] xfs_reclaim_inode+0xdf/0x860 > [ 192.496649][ T369] ? xfs_inode_clear_reclaim_tag+0xa0/0xa0 > [ 192.524188][ T369] ? do_raw_spin_unlock+0x4f/0x250 > [ 192.546852][ T369] xfs_reclaim_inodes_ag+0x505/0xb00 > [ 192.570473][ T369] ? xfs_reclaim_inode+0x860/0x860 > [ 192.592692][ T369] ? mark_held_locks+0xb0/0x110 > [ 192.614287][ T369] ? lockdep_hardirqs_on_prepare+0x38c/0x550 > [ 192.640800][ T369] ? _raw_spin_unlock_irqrestore+0x39/0x40 > [ 192.666695][ T369] ? try_to_wake_up+0xcf/0xf40 > [ 192.688265][ T369] ? migrate_swap_stop+0xc10/0xc10 > [ 192.711966][ T369] ? do_raw_spin_unlock+0x4f/0x250 > [ 192.735032][ T369] xfs_reclaim_inodes_nr+0x93/0xd0 > xfs_reclaim_inodes_nr at fs/xfs/xfs_icache.c:1399 > [ 192.757674][ T369] ? xfs_reclaim_inodes+0x90/0x90 > [ 192.780028][ T369] ? list_lru_count_one+0x177/0x300 > [ 192.803010][ T369] super_cache_scan+0x2fd/0x430 > super_cache_scan at fs/super.c:115 > [ 192.824491][ T369] do_shrink_slab+0x317/0x990 > do_shrink_slab at mm/vmscan.c:514 > [ 192.845160][ T369] shrink_slab+0x3a8/0x4b0 > shrink_slab_memcg at mm/vmscan.c:584 > (inlined by) shrink_slab at mm/vmscan.c:662 > [ 192.864722][ T369] ? do_shrink_slab+0x990/0x990 > [ 192.886137][ T369] ? rcu_is_watching+0x2c/0x80 > [ 192.907289][ T369] ? mem_cgroup_protected+0x228/0x470 > [ 192.931166][ T369] ? vmpressure+0x25/0x290 > [ 192.950595][ T369] shrink_node+0x49c/0x17b0 > [ 192.972332][ T369] balance_pgdat+0x59c/0xed0 > kswapd_shrink_node at mm/vmscan.c:3521 > (inlined by) balance_pgdat at mm/vmscan.c:3670 > [ 192.994918][ T369] ? __node_reclaim+0x950/0x950 > [ 193.018625][ T369] ? lockdep_hardirqs_on_prepare+0x38c/0x550 > [ 193.046566][ T369] ? _raw_spin_unlock_irq+0x1f/0x30 > [ 193.070214][ T369] ? _raw_spin_unlock_irq+0x1f/0x30 > [ 193.093176][ T369] ? finish_task_switch+0x129/0x650 > [ 193.116225][ T369] ? finish_task_switch+0xf2/0x650 > [ 193.138809][ T369] ? rcu_read_lock_bh_held+0xc0/0xc0 > [ 193.163323][ T369] kswapd+0x5a4/0xc40 > [ 193.182690][ T369] ? __kthread_parkme+0x4d/0x1a0 > [ 193.204660][ T369] ? balance_pgdat+0xed0/0xed0 > [ 193.225776][ T369] ? _raw_spin_unlock_irqrestore+0x39/0x40 > [ 193.252306][ T369] ? finish_wait+0x270/0x270 > [ 193.272473][ T369] ? __kthread_parkme+0x4d/0x1a0 > [ 193.294476][ T369] ? __kthread_parkme+0xcc/0x1a0 > [ 193.316704][ T369] ? balance_pgdat+0xed0/0xed0 > [ 193.337808][ T369] kthread+0x358/0x420 > [ 193.355666][ T369] ? kthread_create_worker_on_cpu+0xc0/0xc0 > [ 193.381884][ T369] ret_from_fork+0x22/0x30 > > > --- > > This is part of a gpu lockdep annotation series simply because it > > really helps to catch issues where gpu subsystem locks and primitives > > can deadlock with themselves through allocations and mmu notifiers. > > But aside from that motivation it should be completely free-standing, > > and can land through -mm/-rdma/-hmm or any other tree really whenever. > > -Daniel > > --- > > mm/mmu_notifier.c | 7 ------- > > mm/page_alloc.c | 23 ++++++++++++++--------- > > 2 files changed, 14 insertions(+), 16 deletions(-) > > > > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > > index 06852b896fa6..5d578b9122f8 100644 > > --- a/mm/mmu_notifier.c > > +++ b/mm/mmu_notifier.c > > @@ -612,13 +612,6 @@ int __mmu_notifier_register(struct mmu_notifier *s= ubscription, > > lockdep_assert_held_write(&mm->mmap_sem); > > BUG_ON(atomic_read(&mm->mm_users) <=3D 0); > > > > - if (IS_ENABLED(CONFIG_LOCKDEP)) { > > - fs_reclaim_acquire(GFP_KERNEL); > > - lock_map_acquire(&__mmu_notifier_invalidate_range_start_m= ap); > > - lock_map_release(&__mmu_notifier_invalidate_range_start_m= ap); > > - fs_reclaim_release(GFP_KERNEL); > > - } > > - > > if (!mm->notifier_subscriptions) { > > /* > > * kmalloc cannot be called under mm_take_all_locks(), bu= t we > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 13cc653122b7..f8a222db4a53 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -57,6 +57,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -4124,7 +4125,7 @@ should_compact_retry(struct alloc_context *ac, un= signed int order, int alloc_fla > > static struct lockdep_map __fs_reclaim_map =3D > > STATIC_LOCKDEP_MAP_INIT("fs_reclaim", &__fs_reclaim_map); > > > > -static bool __need_fs_reclaim(gfp_t gfp_mask) > > +static bool __need_reclaim(gfp_t gfp_mask) > > { > > gfp_mask =3D current_gfp_context(gfp_mask); > > > > @@ -4136,10 +4137,6 @@ static bool __need_fs_reclaim(gfp_t gfp_mask) > > if (current->flags & PF_MEMALLOC) > > return false; > > > > - /* We're only interested __GFP_FS allocations for now */ > > - if (!(gfp_mask & __GFP_FS)) > > - return false; > > - > > if (gfp_mask & __GFP_NOLOCKDEP) > > return false; > > > > @@ -4158,15 +4155,23 @@ void __fs_reclaim_release(void) > > > > void fs_reclaim_acquire(gfp_t gfp_mask) > > { > > - if (__need_fs_reclaim(gfp_mask)) > > - __fs_reclaim_acquire(); > > + if (__need_reclaim(gfp_mask)) { > > + if (!(gfp_mask & __GFP_FS)) > > + __fs_reclaim_acquire(); > > + > > + lock_map_acquire(&__mmu_notifier_invalidate_range_start_m= ap); > > + lock_map_release(&__mmu_notifier_invalidate_range_start_m= ap); > > + > > + } > > } > > EXPORT_SYMBOL_GPL(fs_reclaim_acquire); > > > > void fs_reclaim_release(gfp_t gfp_mask) > > { > > - if (__need_fs_reclaim(gfp_mask)) > > - __fs_reclaim_release(); > > + if (__need_reclaim(gfp_mask)) { > > + if (!(gfp_mask & __GFP_FS)) > > + __fs_reclaim_release(); > > + } > > } > > EXPORT_SYMBOL_GPL(fs_reclaim_release); > > #endif > > -- > > 2.26.2 > > > > --=20 Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch