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authorDavid Rientjes <rientjes@google.com>2018-01-31 16:18:32 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-01-31 17:18:38 -0800
commit5ff7091f5a2ca1b7b642ca0dbdede8f693a56926 (patch)
treeaeacdbfded7dd7db9f70766124e45f569ddd4097 /virt
parent3b454ad35043dfbd3b5d2bb92b0991d6342afb44 (diff)
downloadlinux-stericsson-5ff7091f5a2ca1b7b642ca0dbdede8f693a56926.tar.gz
mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks
Commit 4d4bbd8526a8 ("mm, oom_reaper: skip mm structs with mmu notifiers") prevented the oom reaper from unmapping private anonymous memory with the oom reaper when the oom victim mm had mmu notifiers registered. The rationale is that doing mmu_notifier_invalidate_range_{start,end}() around the unmap_page_range(), which is needed, can block and the oom killer will stall forever waiting for the victim to exit, which may not be possible without reaping. That concern is real, but only true for mmu notifiers that have blockable invalidate_range_{start,end}() callbacks. This patch adds a "flags" field to mmu notifier ops that can set a bit to indicate that these callbacks do not block. The implementation is steered toward an expensive slowpath, such as after the oom reaper has grabbed mm->mmap_sem of a still alive oom victim. [rientjes@google.com: mmu_notifier_invalidate_range_end() can also call the invalidate_range() must not block, fix comment] Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1801091339570.240101@chino.kir.corp.google.com [akpm@linux-foundation.org: make mm_has_blockable_invalidate_notifiers() return bool, use rwsem_is_locked()] Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1712141329500.74052@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Christian König <christian.koenig@amd.com> Acked-by: Dimitri Sivanich <sivanich@hpe.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: David Airlie <airlied@linux.ie> Cc: Joerg Roedel <joro@8bytes.org> Cc: Doug Ledford <dledford@redhat.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Mike Marciniszyn <mike.marciniszyn@intel.com> Cc: Sean Hefty <sean.hefty@intel.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d6b9370806f8..35db929f92f0 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -476,6 +476,7 @@ static void kvm_mmu_notifier_release(struct mmu_notifier *mn,
}
static const struct mmu_notifier_ops kvm_mmu_notifier_ops = {
+ .flags = MMU_INVALIDATE_DOES_NOT_BLOCK,
.invalidate_range_start = kvm_mmu_notifier_invalidate_range_start,
.invalidate_range_end = kvm_mmu_notifier_invalidate_range_end,
.clear_flush_young = kvm_mmu_notifier_clear_flush_young,