Linux-stable-mirror November 2018

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1172 discussions

[PATCH v8 1/9] KVM: arm/arm64: Ensure only THP is candidate for adjustment

by Punit Agrawal

PageTransCompoundMap() returns true for hugetlbfs and THP hugepages. This behaviour incorrectly leads to stage 2 faults for unsupported hugepage sizes (e.g., 64K hugepage with 4K pages) to be treated as THP faults. Tighten the check to filter out hugetlbfs pages. This also leads to consistently mapping all unsupported hugepage sizes as PTE level entries at stage 2. Signed-off-by: Punit Agrawal <punit.agrawal(a)arm.com> Reviewed-by: Suzuki Poulose <suzuki.poulose(a)arm.com> Cc: Christoffer Dall <christoffer.dall(a)arm.com> Cc: Marc Zyngier <marc.zyngier(a)arm.com> Cc: stable(a)vger.kernel.org # v4.13+ --- virt/kvm/arm/mmu.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c index 7e477b3cae5b..c23a1b323aad 100644 --- a/virt/kvm/arm/mmu.c +++ b/virt/kvm/arm/mmu.c @@ -1231,8 +1231,14 @@ static bool transparent_hugepage_adjust(kvm_pfn_t *pfnp, phys_addr_t *ipap) { kvm_pfn_t pfn = *pfnp; gfn_t gfn = *ipap >> PAGE_SHIFT; + struct page *page = pfn_to_page(pfn); - if (PageTransCompoundMap(pfn_to_page(pfn))) { + /* + * PageTransCompoungMap() returns true for THP and + * hugetlbfs. Make sure the adjustment is done only for THP + * pages. + */ + if (!PageHuge(page) && PageTransCompoundMap(page)) { unsigned long mask; /* * The address we faulted on is backed by a transparent huge -- 2.18.0

5 years, 5 months

[PATCH AUTOSEL 3.18 01/22] locking/lockdep: Fix debug_locks off performance problem

by Sasha Levin

From: Waiman Long <longman(a)redhat.com> [ Upstream commit 9506a7425b094d2f1d9c877ed5a78f416669269b ] It was found that when debug_locks was turned off because of a problem found by the lockdep code, the system performance could drop quite significantly when the lock_stat code was also configured into the kernel. For instance, parallel kernel build time on a 4-socket x86-64 server nearly doubled. Further analysis into the cause of the slowdown traced back to the frequent call to debug_locks_off() from the __lock_acquired() function probably due to some inconsistent lockdep states with debug_locks off. The debug_locks_off() function did an unconditional atomic xchg to write a 0 value into debug_locks which had already been set to 0. This led to severe cacheline contention in the cacheline that held debug_locks. As debug_locks is being referenced in quite a few different places in the kernel, this greatly slow down the system performance. To prevent that trashing of debug_locks cacheline, lock_acquired() and lock_contended() now checks the state of debug_locks before proceeding. The debug_locks_off() function is also modified to check debug_locks before calling __debug_locks_off(). Signed-off-by: Waiman Long <longman(a)redhat.com> Cc: Andrew Morton <akpm(a)linux-foundation.org> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Paul E. McKenney <paulmck(a)linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz(a)infradead.org> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: Will Deacon <will.deacon(a)arm.com> Link: http://lkml.kernel.org/r/1539913518-15598-1-git-send-email-longman@redhat.c… Signed-off-by: Ingo Molnar <mingo(a)kernel.org> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- kernel/locking/lockdep.c | 4 ++-- lib/debug_locks.c | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index f99008534275..fb90ca3a296e 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3808,7 +3808,7 @@ void lock_contended(struct lockdep_map *lock, unsigned long ip) { unsigned long flags; - if (unlikely(!lock_stat)) + if (unlikely(!lock_stat || !debug_locks)) return; if (unlikely(current->lockdep_recursion)) @@ -3828,7 +3828,7 @@ void lock_acquired(struct lockdep_map *lock, unsigned long ip) { unsigned long flags; - if (unlikely(!lock_stat)) + if (unlikely(!lock_stat || !debug_locks)) return; if (unlikely(current->lockdep_recursion)) diff --git a/lib/debug_locks.c b/lib/debug_locks.c index 96c4c633d95e..124fdf238b3d 100644 --- a/lib/debug_locks.c +++ b/lib/debug_locks.c @@ -37,7 +37,7 @@ EXPORT_SYMBOL_GPL(debug_locks_silent); */ int debug_locks_off(void) { - if (__debug_locks_off()) { + if (debug_locks && __debug_locks_off()) { if (!debug_locks_silent) { console_verbose(); return 1; -- 2.17.1

5 years, 5 months

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Linux-stable-mirror November 2018