This is a note to let you know that I've just added the patch titled
objpool: fix choosing allocation for percpu slots
to the 6.11-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:
objpool-fix-choosing-allocation-for-percpu-slots.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 09b446b6ded4d3801b680fba7d4edcc7ca4d2357
Author: Viktor Malik <vmalik@xxxxxxxxxx>
Date: Mon Aug 26 08:07:18 2024 +0200
objpool: fix choosing allocation for percpu slots
[ Upstream commit aff1871bfc81e9dffa7d2a77e67cc5441cc37f81 ]
objpool intends to use vmalloc for default (non-atomic) allocations of
percpu slots and objects. However, the condition checking if GFP flags
set any bit of GFP_ATOMIC is wrong b/c GFP_ATOMIC is a combination of bits
(__GFP_HIGH|__GFP_KSWAPD_RECLAIM) and so `pool->gfp & GFP_ATOMIC` will
be true if either bit is set. Since GFP_ATOMIC and GFP_KERNEL share the
___GFP_KSWAPD_RECLAIM bit, kmalloc will be used in cases when GFP_KERNEL
is specified, i.e. in all current usages of objpool.
This may lead to unexpected OOM errors since kmalloc cannot allocate
large amounts of memory.
For instance, objpool is used by fprobe rethook which in turn is used by
BPF kretprobe.multi and kprobe.session probe types. Trying to attach
these to all kernel functions with libbpf using
SEC("kprobe.session/*")
int kprobe(struct pt_regs *ctx)
{
[...]
}
fails on objpool slot allocation with ENOMEM.
Fix the condition to truly use vmalloc by default.
Link: https://lore.kernel.org/all/20240826060718.267261-1-vmalik@xxxxxxxxxx/
Fixes: b4edb8d2d464 ("lib: objpool added: ring-array based lockless MPMC")
Signed-off-by: Viktor Malik <vmalik@xxxxxxxxxx>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Reviewed-by: Matt Wu <wuqiang.matt@xxxxxxxxxxxxx>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/lib/objpool.c b/lib/objpool.c
index 234f9d0bd081a..fd108fe0d095a 100644
--- a/lib/objpool.c
+++ b/lib/objpool.c
@@ -76,7 +76,7 @@ objpool_init_percpu_slots(struct objpool_head *pool, int nr_objs,
* mimimal size of vmalloc is one page since vmalloc would
* always align the requested size to page size
*/
- if (pool->gfp & GFP_ATOMIC)
+ if ((pool->gfp & GFP_ATOMIC) == GFP_ATOMIC)
slot = kmalloc_node(size, pool->gfp, cpu_to_node(i));
else
slot = __vmalloc_node(size, sizeof(void *), pool->gfp,
