On Tue, Oct 13, 2026 at 02:46:24PM +0300, Leon Romanovsky wrote:
From: Leon Romanovsky leonro@nvidia.com
dma_buf_phys_vec_to_sgt() clears orig_nents to mark the returned table as DMA-only. Since sg_free_table() uses orig_nents to walk and free the scatterlist, dma_buf_free_sgt() leaks the allocation on every successful map/unmap cycle.
Restore orig_nents from nents before freeing the table. The helper allocates the DMA list directly, so nents retains the allocation count, including for chained scatterlists.
The reported kmemleak output was:
KMEMLEAK LEAK: 2 driver-related leak(s) KMEMLEAK LEAK: unreferenced object 0xff11000125ceff00 (size 32): KMEMLEAK LEAK: comm dtr, pid 4432, jiffies 4295031027 KMEMLEAK LEAK: hex dump (first 32 bytes): KMEMLEAK LEAK: 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ KMEMLEAK LEAK: 00 00 01 00 28 38 00 00 00 10 00 00 00 00 00 00 ....(8.......... KMEMLEAK LEAK: backtrace (crc 4e8077f2): KMEMLEAK LEAK: __kmalloc_noprof+0x451/0x8b0 KMEMLEAK LEAK: __sg_alloc_table+0x2a0/0x4d0 KMEMLEAK LEAK: sg_alloc_table+0x24/0x170 KMEMLEAK LEAK: dma_buf_phys_vec_to_sgt+0x84f/0xed0 KMEMLEAK LEAK: 0xffffffffa1ad21a8 KMEMLEAK LEAK: dma_buf_map_attachment+0x138/0x690 KMEMLEAK LEAK: ib_umem_dmabuf_map_pages+0x249/0xc90 [ib_core] KMEMLEAK LEAK: 0xffffffffa138f8d2 KMEMLEAK LEAK: 0xffffffffa1396abe KMEMLEAK LEAK: 0xffffffffa1331a5f KMEMLEAK LEAK: 0xffffffffa13320dd KMEMLEAK LEAK: 0xffffffffa1ad696d KMEMLEAK LEAK: 0xffffffffa1acecc7 KMEMLEAK LEAK: 0xffffffffa1acfd17 KMEMLEAK LEAK: __x64_sys_ioctl+0x72c/0x11f0 KMEMLEAK LEAK: do_syscall_64+0xa1/0x4f0 KMEMLEAK LEAK: unreferenced object 0xff1100016dbf3a80 (size 32): KMEMLEAK LEAK: comm dtr, pid 4432, jiffies 4295034705 KMEMLEAK LEAK: hex dump (first 32 bytes): KMEMLEAK LEAK: 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ KMEMLEAK LEAK: 00 20 10 00 28 38 00 00 00 10 00 00 00 00 00 00 . ..(8..........
Fixes: 3aa31a8bb11e ("dma-buf: provide phys_vec to scatter-gather mapping routine") Signed-off-by: Leon Romanovsky leonro@nvidia.com
drivers/dma-buf/dma-buf-mapping.c | 2 ++ 1 file changed, 2 insertions(+)
Reminder, thanks