Re: [PATCH 1/4] mm: Check for node_online in node_present_pages
* Srikar Dronamraju [2020-03-17 18:47:50]:
>
> Reported-by: Sachin Sant
> Tested-by: Sachin Sant
> Signed-off-by: Srikar Dronamraju
> ---
> include/linux/mmzone.h | 6 --
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index f3f264826423..88078a3b95e5 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -756,8 +756,10 @@ typedef struct pglist_data {
> atomic_long_t vm_stat[NR_VM_NODE_STAT_ITEMS];
> } pg_data_t;
>
> -#define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
> -#define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
> +#define node_present_pages(nid) \
> + (node_online(nid) ? NODE_DATA(nid)->node_present_pages : 0)
> +#define node_spanned_pages(nid) \
> + (node_online(nid) ? NODE_DATA(nid)->node_spanned_pages : 0)
> #ifdef CONFIG_FLAT_NODE_MEM_MAP
> #define pgdat_page_nr(pgdat, pagenr) ((pgdat)->node_mem_map + (pagenr))
> #else
If we indeed start having pgdat/NODE_DATA for even offline nodes as Michal
Hocko, then we may not this particular patch.
--
Thanks and Regards
Srikar Dronamraju
[PATCH 1/4] mm: Check for node_online in node_present_pages
Calling a kmalloc_node on a possible node which is not yet onlined can
lead to panic. Currently node_present_pages() doesn't verify the node is
online before accessing the pgdat for the node. However pgdat struct may
not be available resulting in a crash.
NIP [c03d55f4] ___slab_alloc+0x1f4/0x760
LR [c03d5b94] __slab_alloc+0x34/0x60
Call Trace:
[c008b3783960] [c03d5734] ___slab_alloc+0x334/0x760 (unreliable)
[c008b3783a40] [c03d5b94] __slab_alloc+0x34/0x60
[c008b3783a70] [c03d6fa0] __kmalloc_node+0x110/0x490
[c008b3783af0] [c03443d8] kvmalloc_node+0x58/0x110
[c008b3783b30] [c03fee38] mem_cgroup_css_online+0x108/0x270
[c008b3783b90] [c0235aa8] online_css+0x48/0xd0
[c008b3783bc0] [c023eaec] cgroup_apply_control_enable+0x2ec/0x4d0
[c008b3783ca0] [c0242318] cgroup_mkdir+0x228/0x5f0
[c008b3783d10] [c051e170] kernfs_iop_mkdir+0x90/0xf0
[c008b3783d50] [c043dc00] vfs_mkdir+0x110/0x230
[c008b3783da0] [c0441c90] do_mkdirat+0xb0/0x1a0
[c008b3783e20] [c000b278] system_call+0x5c/0x68
Fix this by verifying the node is online before accessing the pgdat
structure. Fix the same for node_spanned_pages() too.
Cc: Andrew Morton
Cc: linux...@kvack.org
Cc: Mel Gorman
Cc: Michael Ellerman
Cc: Sachin Sant
Cc: Michal Hocko
Cc: Christopher Lameter
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Joonsoo Kim
Cc: Kirill Tkhai
Cc: Vlastimil Babka
Cc: Srikar Dronamraju
Cc: Bharata B Rao
Reported-by: Sachin Sant
Tested-by: Sachin Sant
Signed-off-by: Srikar Dronamraju
---
include/linux/mmzone.h | 6 --
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index f3f264826423..88078a3b95e5 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -756,8 +756,10 @@ typedef struct pglist_data {
atomic_long_t vm_stat[NR_VM_NODE_STAT_ITEMS];
} pg_data_t;
-#define node_present_pages(nid)(NODE_DATA(nid)->node_present_pages)
-#define node_spanned_pages(nid)(NODE_DATA(nid)->node_spanned_pages)
+#define node_present_pages(nid)\
+ (node_online(nid) ? NODE_DATA(nid)->node_present_pages : 0)
+#define node_spanned_pages(nid)\
+ (node_online(nid) ? NODE_DATA(nid)->node_spanned_pages : 0)
#ifdef CONFIG_FLAT_NODE_MEM_MAP
#define pgdat_page_nr(pgdat, pagenr) ((pgdat)->node_mem_map + (pagenr))
#else
--
2.18.1
