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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: linux-rdma@vger.kernel.org,
	"Intel Graphics Development" <intel-gfx@lists.freedesktop.org>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	amd-gfx@lists.freedesktop.org,
	"Christian König" <christian.koenig@amd.com>,
	linux-mm@kvack.org,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Thomas Hellström" <thomas_os@shipmail.org>
Subject: Re: [PATCH] mm: Track mmu notifiers in fs_reclaim_acquire/release
Date: Thu, 11 Jun 2020 11:29:53 -0300
Message-ID: <20200611142953.GA1419658@ziepe.ca> (raw)
In-Reply-To: <20200610194101.1668038-1-daniel.vetter@ffwll.ch>

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 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.
> 
> 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 Hellström (Intel) <thomas_os@shipmail.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Jason Gunthorpe <jgg@mellanox.com>
> Cc: linux-mm@kvack.org
> Cc: linux-rdma@vger.kernel.org
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Christian König <christian.koenig@amd.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
> 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

I'm still not totally clear on how all the GFP flags map to
different behaviors, but this seems plausible to me

At this point it should go through Andrew's tree, thanks

Acked-by: Jason Gunthorpe <jgg@mellanox.com> # For mmu_notifiers

Jason
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Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-04  8:12 [PATCH 00/18] dma-fence lockdep annotations, round 2 Daniel Vetter
2020-06-04  8:12 ` [PATCH 01/18] mm: Track mmu notifiers in fs_reclaim_acquire/release Daniel Vetter
2020-06-10 12:01   ` Thomas Hellström (Intel)
2020-06-10 12:25     ` [Intel-gfx] " Daniel Vetter
2020-06-10 19:41   ` [PATCH] " Daniel Vetter
2020-06-11 14:29     ` Jason Gunthorpe [this message]
2020-06-21 17:42     ` Qian Cai
2020-06-21 18:07       ` Daniel Vetter
2020-06-21 20:01         ` Daniel Vetter
2020-06-21 22:09           ` Qian Cai
2020-06-23 16:17           ` Qian Cai
2020-06-23 22:13             ` Daniel Vetter
2020-06-23 22:29               ` Qian Cai
2020-06-23 22:31       ` Dave Chinner
2020-06-23 22:36         ` Daniel Vetter
2020-06-21 17:00   ` [PATCH 01/18] " Qian Cai
2020-06-21 17:28     ` Daniel Vetter
2020-06-21 17:46       ` Qian Cai
2020-06-04  8:12 ` [PATCH 02/18] dma-buf: minor doc touch-ups Daniel Vetter
2020-06-10 13:07   ` Thomas Hellström (Intel)
2020-06-04  8:12 ` [PATCH 03/18] dma-fence: basic lockdep annotations Daniel Vetter
2020-06-04  8:57   ` Thomas Hellström (Intel)
2020-06-04  9:21     ` Daniel Vetter
2020-06-04  9:26       ` Chris Wilson
2020-06-04  9:36         ` [Intel-gfx] " Daniel Vetter
2020-06-05 13:29   ` [PATCH] " Daniel Vetter
2020-06-05 14:30     ` Thomas Hellström (Intel)
2020-06-11  9:57     ` Maarten Lankhorst
2020-06-10 14:21   ` [Intel-gfx] [PATCH 03/18] " Tvrtko Ursulin
2020-06-10 15:17     ` Daniel Vetter
2020-06-11 10:36       ` Tvrtko Ursulin
2020-06-11 11:29         ` Daniel Vetter
2020-06-11 14:29           ` Tvrtko Ursulin
2020-06-11 15:03             ` Daniel Vetter
2020-06-11  8:00   ` Chris Wilson
2020-06-11  8:44     ` Dave Airlie
2020-06-11  9:01       ` [Intel-gfx] " Daniel Stone
2020-06-19  8:25         ` Chris Wilson
2020-06-19  8:51           ` Daniel Vetter
2020-06-19  9:13             ` Chris Wilson
2020-06-19  9:43               ` Daniel Vetter
2020-06-19 13:12                 ` Chris Wilson
2020-06-22  9:16                   ` Daniel Vetter
2020-07-09  7:29                 ` Daniel Stone
2020-07-09  8:01                   ` Daniel Vetter
2020-06-12  7:06   ` [PATCH] " Daniel Vetter
2020-06-04  8:12 ` [PATCH 04/18] dma-fence: prime " Daniel Vetter
2020-06-11  7:30   ` [Linaro-mm-sig] " Thomas Hellström (Intel)
2020-06-11  8:34     ` Daniel Vetter
2020-06-11 14:15       ` Jason Gunthorpe
2020-06-11 23:35         ` Felix Kuehling
2020-06-12  5:11           ` Daniel Vetter
2020-06-19 18:13           ` Jerome Glisse
2020-06-23  7:39           ` Daniel Vetter
2020-06-23 18:44             ` Felix Kuehling
2020-06-23 19:02               ` Daniel Vetter
2020-06-16 12:07         ` Daniel Vetter
2020-06-16 14:53           ` Jason Gunthorpe
2020-06-17  7:57             ` Daniel Vetter
2020-06-17 15:29               ` Jason Gunthorpe
2020-06-18 14:42                 ` Daniel Vetter
2020-06-17  6:48           ` Daniel Vetter
2020-06-17 15:28             ` Jason Gunthorpe
2020-06-18 15:00               ` Daniel Vetter
2020-06-18 17:23                 ` Jason Gunthorpe
2020-06-19  7:22                   ` Daniel Vetter
2020-06-19 11:39                     ` Jason Gunthorpe
2020-06-19 15:06                       ` Daniel Vetter
2020-06-19 15:15                         ` Jason Gunthorpe
2020-06-19 16:19                           ` Daniel Vetter
2020-06-19 17:23                             ` Jason Gunthorpe
2020-06-19 18:09                               ` Jerome Glisse
2020-06-19 18:18                                 ` Jason Gunthorpe
2020-06-19 19:48                                   ` Felix Kuehling
2020-06-19 19:55                                     ` Jason Gunthorpe
2020-06-19 20:03                                       ` Felix Kuehling
2020-06-19 20:31                                       ` Jerome Glisse
2020-06-22 11:46                                         ` Jason Gunthorpe
2020-06-22 20:15                                           ` Jerome Glisse
2020-06-23  0:02                                             ` Jason Gunthorpe
2020-06-19 20:10                                   ` Jerome Glisse
2020-06-19 20:43                                     ` Daniel Vetter
2020-06-19 20:59                                       ` Jerome Glisse
2020-06-23  0:05                                     ` Jason Gunthorpe
2020-06-19 19:11                                 ` Alex Deucher
2020-06-19 19:30                                   ` Felix Kuehling
2020-06-19 19:40                                     ` Jerome Glisse
2020-06-19 19:51                                     ` Jason Gunthorpe
2020-06-12  7:01   ` [PATCH] " Daniel Vetter
2020-06-04  8:12 ` [PATCH 05/18] drm/vkms: Annotate vblank timer Daniel Vetter
2020-06-04  8:12 ` [PATCH 06/18] drm/vblank: Annotate with dma-fence signalling section Daniel Vetter
2020-06-04  8:12 ` [PATCH 07/18] drm/atomic-helper: Add dma-fence annotations Daniel Vetter
2020-06-04  8:12 ` [PATCH 08/18] drm/amdgpu: add dma-fence annotations to atomic commit path Daniel Vetter
2020-06-23 10:51   ` Daniel Vetter
2020-06-04  8:12 ` [PATCH 09/18] drm/scheduler: use dma-fence annotations in main thread Daniel Vetter
2020-06-04  8:12 ` [PATCH 10/18] drm/amdgpu: use dma-fence annotations in cs_submit() Daniel Vetter
2020-06-04  8:12 ` [PATCH 11/18] drm/amdgpu: s/GFP_KERNEL/GFP_ATOMIC in scheduler code Daniel Vetter
2020-06-04  8:12 ` [PATCH 12/18] drm/amdgpu: DC also loves to allocate stuff where it shouldn't Daniel Vetter
2020-06-04  8:12 ` [PATCH 13/18] drm/amdgpu/dc: Stop dma_resv_lock inversion in commit_tail Daniel Vetter
2020-06-05  8:30   ` Pierre-Eric Pelloux-Prayer
2020-06-05 12:41     ` Daniel Vetter
2020-06-04  8:12 ` [PATCH 14/18] drm/scheduler: use dma-fence annotations in tdr work Daniel Vetter
2020-06-04  8:12 ` [PATCH 15/18] drm/amdgpu: use dma-fence annotations for gpu reset code Daniel Vetter
2020-06-04  8:12 ` [PATCH 16/18] Revert "drm/amdgpu: add fbdev suspend/resume on gpu reset" Daniel Vetter
2020-06-04  8:12 ` [PATCH 17/18] drm/amdgpu: gpu recovery does full modesets Daniel Vetter
2020-06-04  8:12 ` [PATCH 18/18] drm/i915: Annotate dma_fence_work Daniel Vetter

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