On Thu, Jul 03, 2025 at 12:33:12AM +0900, Jeongjun Park wrote:
commit 5c5f0468d172ddec2e333d738d2a1f85402cf0bc upstream.
The following data-race was found in show_numa_info():
================================================================== BUG: KCSAN: data-race in vmalloc_info_show / vmalloc_info_show
read to 0xffff88800971fe30 of 4 bytes by task 8289 on cpu 0: show_numa_info mm/vmalloc.c:4936 [inline] vmalloc_info_show+0x5a8/0x7e0 mm/vmalloc.c:5016 seq_read_iter+0x373/0xb40 fs/seq_file.c:230 proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 ....
write to 0xffff88800971fe30 of 4 bytes by task 8287 on cpu 1: show_numa_info mm/vmalloc.c:4934 [inline] vmalloc_info_show+0x38f/0x7e0 mm/vmalloc.c:5016 seq_read_iter+0x373/0xb40 fs/seq_file.c:230 proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 ....
value changed: 0x0000008f -> 0x00000000
According to this report,there is a read/write data-race because m->private is accessible to multiple CPUs. To fix this, instead of allocating the heap in proc_vmalloc_init() and passing the heap address to m->private, vmalloc_info_show() should allocate the heap.
Link: https://lkml.kernel.org/r/20250508165620.15321-1-aha310510@gmail.com Fixes: 8e1d743 ("mm: vmalloc: support multiple nodes in vmallocinfo")
Why did you change this line?
Signed-off-by: Jeongjun Park aha310510@gmail.com Suggested-by: Eric Dumazet edumazet@google.com Suggested-by: Andrew Morton akpm@linux-foundation.org Reviewed-by: "Uladzislau Rezki (Sony)" urezki@gmail.com Signed-off-by: Andrew Morton akpm@linux-foundation.org
mm/vmalloc.c | 63 +++++++++++++++++++++++++++++----------------------- 1 file changed, 35 insertions(+), 28 deletions(-)
Please document what you changed from the original version, as this does not match what is in Linus's tree.
thanks,
greg k-h