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
Change-Id: I57d4e9c7ce5aeb3273574026da2a8b737ef0b809
Link: http://lkml.kernel.org/r/1479474236-4139-10-git-send-email-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jisheng Zhang <jszhang@marvell.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: John Dias <joaodias@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: f9e09977671b618aeb25ddc0d4c9a84d5b5cde9d
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 2153e4d..039cb5d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -667,7 +667,7 @@
* 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);
@@ -721,9 +721,9 @@
*/
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);
}
}
@@ -732,10 +732,10 @@
*/
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);
}
/*
@@ -1124,11 +1124,11 @@
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);