[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC PATCH] mm, oom: distinguish blockable mode for mmu notifiers
On Fri 22-06-18 17:13:02, Christian König wrote: > Hi Michal, > > [Adding Felix as well] > > Well first of all you have a misconception why at least the AMD graphics > driver need to be able to sleep in an MMU notifier: We need to sleep because > we need to wait for hardware operations to finish and *NOT* because we need > to wait for locks. > > I'm not sure if your flag now means that you generally can't sleep in MMU > notifiers any more, but if that's the case at least AMD hardware will break > badly. In our case the approach of waiting for a short time for the process > to be reaped and then select another victim actually sounds like the right > thing to do. Well, I do not need to make the notifier code non blocking all the time. All I need is to ensure that it won't sleep if the flag says so and return -EAGAIN instead. So here is what I do for amdgpu: > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c > > index 83e344fbb50a..d138a526feff 100644 > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c > > @@ -136,12 +136,18 @@ void amdgpu_mn_unlock(struct amdgpu_mn *mn) > > * > > * Take the rmn read side lock. > > */ > > -static void amdgpu_mn_read_lock(struct amdgpu_mn *rmn) > > +static int amdgpu_mn_read_lock(struct amdgpu_mn *rmn, bool blockable) > > { > > - mutex_lock(&rmn->read_lock); > > + if (blockable) > > + mutex_lock(&rmn->read_lock); > > + else if (!mutex_trylock(&rmn->read_lock)) > > + return -EAGAIN; > > + > > if (atomic_inc_return(&rmn->recursion) == 1) > > down_read_non_owner(&rmn->lock); > > mutex_unlock(&rmn->read_lock); > > + > > + return 0; > > } > > /** > > @@ -197,10 +203,11 @@ static void amdgpu_mn_invalidate_node(struct > > amdgpu_mn_node *node, > > * We block for all BOs between start and end to be idle and > > * unmap them by move them into system domain again. > > */ > > -static void amdgpu_mn_invalidate_range_start_gfx(struct mmu_notifier *mn, > > +static int amdgpu_mn_invalidate_range_start_gfx(struct mmu_notifier *mn, > > struct mm_struct *mm, > > unsigned long start, > > - unsigned long end) > > + unsigned long end, > > + bool blockable) > > { > > struct amdgpu_mn *rmn = container_of(mn, struct amdgpu_mn, mn); > > struct interval_tree_node *it; > > @@ -208,7 +215,11 @@ static void > > amdgpu_mn_invalidate_range_start_gfx(struct mmu_notifier *mn, > > /* notification is exclusive, but interval is inclusive */ > > end -= 1; > > - amdgpu_mn_read_lock(rmn); > > + /* TODO we should be able to split locking for interval tree and > > + * amdgpu_mn_invalidate_node > > + */ > > + if (amdgpu_mn_read_lock(rmn, blockable)) > > + return -EAGAIN; > > it = interval_tree_iter_first(&rmn->objects, start, end); > > while (it) { > > @@ -219,6 +230,8 @@ static void amdgpu_mn_invalidate_range_start_gfx(struct > > mmu_notifier *mn, > > amdgpu_mn_invalidate_node(node, start, end); > > } > > + > > + return 0; > > } > > /** > > @@ -233,10 +246,11 @@ static void > > amdgpu_mn_invalidate_range_start_gfx(struct mmu_notifier *mn, > > * necessitates evicting all user-mode queues of the process. The BOs > > * are restorted in amdgpu_mn_invalidate_range_end_hsa. > > */ > > -static void amdgpu_mn_invalidate_range_start_hsa(struct mmu_notifier *mn, > > +static int amdgpu_mn_invalidate_range_start_hsa(struct mmu_notifier *mn, > > struct mm_struct *mm, > > unsigned long start, > > - unsigned long end) > > + unsigned long end, > > + bool blockable) > > { > > struct amdgpu_mn *rmn = container_of(mn, struct amdgpu_mn, mn); > > struct interval_tree_node *it; > > @@ -244,7 +258,8 @@ static void amdgpu_mn_invalidate_range_start_hsa(struct > > mmu_notifier *mn, > > /* notification is exclusive, but interval is inclusive */ > > end -= 1; > > - amdgpu_mn_read_lock(rmn); > > + if (amdgpu_mn_read_lock(rmn, blockable)) > > + return -EAGAIN; > > it = interval_tree_iter_first(&rmn->objects, start, end); > > while (it) { > > @@ -262,6 +277,8 @@ static void amdgpu_mn_invalidate_range_start_hsa(struct > > mmu_notifier *mn, > > amdgpu_amdkfd_evict_userptr(mem, mm); > > } > > } > > + > > + return 0; > > } > > /** -- Michal Hocko SUSE Labs _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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