[PATCH v2 mm] mm: fix BUG splat with kvmalloc + GFP_ATOMIC

Florian Westphal
2022-09-26T15:17:39Z

Martin Zaharinov reports BUG with 5.19.10 kernel:
kernel BUG at mm/vmalloc.c:2437!
invalid opcode: 0000 [#1] SMP
CPU: 28 PID: 0 Comm: swapper/28 Tainted: G W O 5.19.9 #1
[..]
RIP: 0010:__get_vm_area_node+0x120/0x130
__vmalloc_node_range+0x96/0x1e0
kvmalloc_node+0x92/0xb0
bucket_table_alloc.isra.0+0x47/0x140
rhashtable_try_insert+0x3a4/0x440
rhashtable_insert_slow+0x1b/0x30
[..]

bucket_table_alloc uses kvzalloc(GPF_ATOMIC). If kmalloc fails, this now
falls through to vmalloc and hits code paths that assume GFP_KERNEL.

Reported-by: Martin Zaharinov <micron10@gmail.com>
Fixes: a421ef303008 ("mm: allow !GFP_KERNEL allocations for kvmalloc")
Suggested-by: Michal Hocko <mhocko@suse.com>
Link: https://lore.kernel.org/linux-mm/Yy3MS2uhSgjF47dy@pc636/T/#t
Signed-off-by: Florian Westphal <fw@strlen.de>
---
mm/util.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/mm/util.c b/mm/util.c
index c9439c66d8cf..346e40177bc6 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -619,6 +619,10 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node)
if (ret || size <= PAGE_SIZE)
return ret;

+ /* non-sleeping allocations are not supported by vmalloc */
+ if (!gfpflags_allow_blocking(flags))
+ return NULL;
+
/* Don't even allow crazy sizes */
if (unlikely(size > INT_MAX)) {
WARN_ON_ONCE(!(flags & __GFP_NOWARN));
--
2.35.1