From f9e09977671b618aeb25ddc0d4c9a84d5b5cde9d Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 12 Dec 2016 16:44:23 -0800 Subject: mm: turn vmap_purge_lock into a mutex The purge_lock spinlock causes high latencies with non RT kernel. This has been reported multiple times on lkml [1] [2] and affects applications like audio. This patch replaces it with a mutex to allow preemption while holding the lock. Thanks to Joel Fernandes for the detailed report and analysis as well as an earlier attempt at fixing this issue. [1] http://lists.openwall.net/linux-kernel/2016/03/23/29 [2] https://lkml.org/lkml/2016/10/9/59 Link: http://lkml.kernel.org/r/1479474236-4139-10-git-send-email-hch@lst.de Signed-off-by: Christoph Hellwig Tested-by: Jisheng Zhang Cc: Andrey Ryabinin Cc: Joel Fernandes Cc: Chris Wilson Cc: John Dias Cc: Thomas Gleixner Cc: "H. Peter Anvin" Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmalloc.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'mm/vmalloc.c') diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 3308007d8427..d3c1f5ee48b4 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -606,7 +606,7 @@ static atomic_t vmap_lazy_nr = ATOMIC_INIT(0); * by this look, but we want to avoid concurrent calls for performance * reasons and to make the pcpu_get_vm_areas more deterministic. */ -static DEFINE_SPINLOCK(vmap_purge_lock); +static DEFINE_MUTEX(vmap_purge_lock); /* for per-CPU blocks */ static void purge_fragmented_blocks_allcpus(void); @@ -660,9 +660,9 @@ static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end) */ static void try_purge_vmap_area_lazy(void) { - if (spin_trylock(&vmap_purge_lock)) { + if (mutex_trylock(&vmap_purge_lock)) { __purge_vmap_area_lazy(ULONG_MAX, 0); - spin_unlock(&vmap_purge_lock); + mutex_unlock(&vmap_purge_lock); } } @@ -671,10 +671,10 @@ static void try_purge_vmap_area_lazy(void) */ static void purge_vmap_area_lazy(void) { - spin_lock(&vmap_purge_lock); + mutex_lock(&vmap_purge_lock); purge_fragmented_blocks_allcpus(); __purge_vmap_area_lazy(ULONG_MAX, 0); - spin_unlock(&vmap_purge_lock); + mutex_unlock(&vmap_purge_lock); } /* @@ -1063,11 +1063,11 @@ void vm_unmap_aliases(void) rcu_read_unlock(); } - spin_lock(&vmap_purge_lock); + mutex_lock(&vmap_purge_lock); purge_fragmented_blocks_allcpus(); if (!__purge_vmap_area_lazy(start, end) && flush) flush_tlb_kernel_range(start, end); - spin_unlock(&vmap_purge_lock); + mutex_unlock(&vmap_purge_lock); } EXPORT_SYMBOL_GPL(vm_unmap_aliases); -- cgit