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Subject[PATCH 4/6] mm: kvmalloc support __GFP_RETRY_MAYFAIL for all sizes
Date
From: Michal Hocko <mhocko@suse.com>

Now that __GFP_RETRY_MAYFAIL has a reasonable semantic regardless of the
request size we can drop the hackish implementation for !costly orders.
__GFP_RETRY_MAYFAIL retries as long as the reclaim makes a forward
progress and backs of when we are out of memory for the requested size.
Therefore we do not need to enforce__GFP_NORETRY for !costly orders just
to silent the oom killer anymore.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
mm/util.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/mm/util.c b/mm/util.c
index 6520f2d4a226..ee250e2cde34 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -339,9 +339,9 @@ EXPORT_SYMBOL(vm_mmap);
* Uses kmalloc to get the memory but if the allocation fails then falls back
* to the vmalloc allocator. Use kvfree for freeing the memory.
*
- * Reclaim modifiers - __GFP_NORETRY and __GFP_NOFAIL are not supported. __GFP_RETRY_MAYFAIL
- * is supported only for large (>32kB) allocations, and it should be used only if
- * kmalloc is preferable to the vmalloc fallback, due to visible performance drawbacks.
+ * Reclaim modifiers - __GFP_NORETRY and __GFP_NOFAIL are not supported.
+ * __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is
+ * preferable to the vmalloc fallback, due to visible performance drawbacks.
*
* Any use of gfp flags outside of GFP_KERNEL should be consulted with mm people.
*/
@@ -366,13 +366,7 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node)
if (size > PAGE_SIZE) {
kmalloc_flags |= __GFP_NOWARN;

- /*
- * We have to override __GFP_RETRY_MAYFAIL by __GFP_NORETRY for !costly
- * requests because there is no other way to tell the allocator
- * that we want to fail rather than retry endlessly.
- */
- if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL) ||
- (size <= PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER))
+ if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL))
kmalloc_flags |= __GFP_NORETRY;
}

--
2.11.0
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