This is a note to let you know that I've just added the patch titled
mm: kvmalloc does not fallback to vmalloc for incompatible gfp flags
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-kvmalloc-does-not-fallback-to-vmalloc-for-incompatible-gfp-flags.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ce91f6ee5b3bbbad8caff61b1c46d845c8db19bf Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@xxxxxxxx>
Date: Thu, 7 Jun 2018 17:09:40 -0700
Subject: mm: kvmalloc does not fallback to vmalloc for incompatible gfp flags
From: Michal Hocko <mhocko@xxxxxxxx>
commit ce91f6ee5b3bbbad8caff61b1c46d845c8db19bf upstream.
kvmalloc warned about incompatible gfp_mask to catch abusers (mostly
GFP_NOFS) with an intention that this will motivate authors of the code
to fix those. Linus argues that this just motivates people to do even
more hacks like
if (gfp == GFP_KERNEL)
kvmalloc
else
kmalloc
I haven't seen this happening much (Linus pointed to bucket_lock special
cases an atomic allocation but my git foo hasn't found much more) but it
is true that we can grow those in future. Therefore Linus suggested to
simply not fallback to vmalloc for incompatible gfp flags and rather
stick with the kmalloc path.
Link: http://lkml.kernel.org/r/20180601115329.27807-1-mhocko@xxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Tom Herbert <tom@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Rishabh Bhatnagar <risbhat@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/util.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/mm/util.c
+++ b/mm/util.c
@@ -400,7 +400,8 @@ EXPORT_SYMBOL(vm_mmap);
* __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.
+ * Please note that any use of gfp flags outside of GFP_KERNEL is careful to not
+ * fall back to vmalloc.
*/
void *kvmalloc_node(size_t size, gfp_t flags, int node)
{
@@ -411,7 +412,8 @@ void *kvmalloc_node(size_t size, gfp_t f
* vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
* so the given set of flags has to be compatible.
*/
- WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL);
+ if ((flags & GFP_KERNEL) != GFP_KERNEL)
+ return kmalloc_node(size, flags, node);
/*
* We want to attempt a large physically contiguous block first because
Patches currently in stable-queue which might be from mhocko@xxxxxxxx are
queue-4.14/mm-kvmalloc-does-not-fallback-to-vmalloc-for-incompatible-gfp-flags.patch
