From: Sergey Senozhatsky <senozhatsky@chromium.org> To: Sergey Senozhatsky <senozhatsky@chromium.org>, Matthew Auld <matthew.william.auld@gmail.com>, Jani Nikula <jani.nikula@linux.intel.com>, Joonas Lahtinen <joonas.lahtinen@linux.intel.com>, David Airlie <airlied@linux.ie>, Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: drm/i915: __GFP_RETRY_MAYFAIL allocations in stable kernels Date: Fri, 18 Jun 2021 11:29:30 +0900 [thread overview] Message-ID: <YMwFCoHzjnuH80p6@google.com> (raw) In-Reply-To: <YMuGGqs4cDotxuKO@phenom.ffwll.local> On (21/06/17 19:27), Daniel Vetter wrote: > > > > So can all allocations in gen8_init_scratch() use > > GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN > > Yeah that looks all fairly broken tbh. The only thing I didn't know was > that GFP_DMA32 wasn't a full gfp mask with reclaim bits set as needed. I > guess it would be clearer if we use GFP_KERNEL | __GFP_DMA32 for these. Looks good. > The commit that introduced a lot of this, including I915_GFP_ALLOW_FAIL > seems to be > > commit 1abb70f5955d1a9021f96359a2c6502ca569b68d > Author: Chris Wilson <chris@chris-wilson.co.uk> > Date: Tue May 22 09:36:43 2018 +0100 > > drm/i915/gtt: Allow pagedirectory allocations to fail > > which used a selftest as justification, not real world workloads, so looks > rather dubious. Exactly, the commit we landed internally partially reverts 1abb70f5955 in 4.19 and 5.4 kernels. I don't mind I915_GFP_ALLOW_FAIL and so on, I kept those bits, but we need reclaim. I can reproduce cases when order:0 allocation fails with __GFP_HIGHMEM|__GFP_RETRY_MAYFAIL but succeeds with GFP_KERNEL|__GFP_HIGHMEM|__GFP_RETRY_MAYFAIL ON a side note, I'm not very sure if __GFP_RETRY_MAYFAIL is actually needed. Especially seeing it in syscalls is a bit uncommon: drm_ioctl() i915_gem_context_create_ioctl() i915_gem_create_context() i915_ppgtt_create() setup_scratch_page() // __GFP_RETRY_MAYFAIL But with GFP_KERNEL at least it tries to make some reclaim progress between retries, so it seems to be good enough.
WARNING: multiple messages have this Message-ID (diff)
From: Sergey Senozhatsky <senozhatsky@chromium.org> To: Sergey Senozhatsky <senozhatsky@chromium.org>, Matthew Auld <matthew.william.auld@gmail.com>, Jani Nikula <jani.nikula@linux.intel.com>, Joonas Lahtinen <joonas.lahtinen@linux.intel.com>, David Airlie <airlied@linux.ie>, Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [Intel-gfx] drm/i915: __GFP_RETRY_MAYFAIL allocations in stable kernels Date: Fri, 18 Jun 2021 11:29:30 +0900 [thread overview] Message-ID: <YMwFCoHzjnuH80p6@google.com> (raw) In-Reply-To: <YMuGGqs4cDotxuKO@phenom.ffwll.local> On (21/06/17 19:27), Daniel Vetter wrote: > > > > So can all allocations in gen8_init_scratch() use > > GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN > > Yeah that looks all fairly broken tbh. The only thing I didn't know was > that GFP_DMA32 wasn't a full gfp mask with reclaim bits set as needed. I > guess it would be clearer if we use GFP_KERNEL | __GFP_DMA32 for these. Looks good. > The commit that introduced a lot of this, including I915_GFP_ALLOW_FAIL > seems to be > > commit 1abb70f5955d1a9021f96359a2c6502ca569b68d > Author: Chris Wilson <chris@chris-wilson.co.uk> > Date: Tue May 22 09:36:43 2018 +0100 > > drm/i915/gtt: Allow pagedirectory allocations to fail > > which used a selftest as justification, not real world workloads, so looks > rather dubious. Exactly, the commit we landed internally partially reverts 1abb70f5955 in 4.19 and 5.4 kernels. I don't mind I915_GFP_ALLOW_FAIL and so on, I kept those bits, but we need reclaim. I can reproduce cases when order:0 allocation fails with __GFP_HIGHMEM|__GFP_RETRY_MAYFAIL but succeeds with GFP_KERNEL|__GFP_HIGHMEM|__GFP_RETRY_MAYFAIL ON a side note, I'm not very sure if __GFP_RETRY_MAYFAIL is actually needed. Especially seeing it in syscalls is a bit uncommon: drm_ioctl() i915_gem_context_create_ioctl() i915_gem_create_context() i915_ppgtt_create() setup_scratch_page() // __GFP_RETRY_MAYFAIL But with GFP_KERNEL at least it tries to make some reclaim progress between retries, so it seems to be good enough. _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
next prev parent reply other threads:[~2021-06-18 2:29 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-14 12:45 drm/i915: __GFP_RETRY_MAYFAIL allocations in stable kernels Sergey Senozhatsky 2021-06-14 12:45 ` [Intel-gfx] " Sergey Senozhatsky 2021-06-14 12:45 ` Sergey Senozhatsky 2021-06-14 23:38 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for " Patchwork 2021-06-17 17:27 ` Daniel Vetter 2021-06-17 17:27 ` [Intel-gfx] " Daniel Vetter 2021-06-17 17:27 ` Daniel Vetter 2021-06-18 2:29 ` Sergey Senozhatsky [this message] 2021-06-18 2:29 ` [Intel-gfx] " Sergey Senozhatsky 2021-06-18 15:46 ` Matthew Auld 2021-06-18 15:46 ` [Intel-gfx] " Matthew Auld 2021-06-18 15:46 ` Matthew Auld 2021-06-21 14:10 ` Daniel Vetter 2021-06-21 14:10 ` [Intel-gfx] " Daniel Vetter 2021-06-21 14:10 ` Daniel Vetter
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