From 763b218ddfaf56761c19923beb7e16656f66ec62 Mon Sep 17 00:00:00 2001
From: Joel Fernandes <joelaf@google.com>
Date: Mon, 12 Dec 2016 16:44:26 -0800
Subject: [PATCH] mm: add preempt points into __purge_vmap_area_lazy()
Use cond_resched_lock to avoid holding the vmap_area_lock for a
potentially long time and thus creating bad latencies for various
workloads.
[hch: split from a larger patch by Joel, wrote the crappy changelog]
Link: http://lkml.kernel.org/r/1479474236-4139-11-git-send-email-hch@lst.de
Signed-off-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jisheng Zhang <jszhang@marvell.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.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>
---
mm/vmalloc.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d3c1f5ee48b48..a5584384eabc1 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -628,7 +628,7 @@ static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end)
struct llist_node *valist;
struct vmap_area *va;
struct vmap_area *n_va;
- int nr = 0;
+ bool do_free = false;
lockdep_assert_held(&vmap_purge_lock);
@@ -638,18 +638,22 @@ static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end)
start = va->va_start;
if (va->va_end > end)
end = va->va_end;
- nr += (va->va_end - va->va_start) >> PAGE_SHIFT;
+ do_free = true;
}
- if (!nr)
+ if (!do_free)
return false;
- atomic_sub(nr, &vmap_lazy_nr);
flush_tlb_kernel_range(start, end);
spin_lock(&vmap_area_lock);
- llist_for_each_entry_safe(va, n_va, valist, purge_list)
+ llist_for_each_entry_safe(va, n_va, valist, purge_list) {
+ int nr = (va->va_end - va->va_start) >> PAGE_SHIFT;
+
__free_vmap_area(va);
+ atomic_sub(nr, &vmap_lazy_nr);
+ cond_resched_lock(&vmap_area_lock);
+ }
spin_unlock(&vmap_area_lock);
return true;
}
--
GitLab