| Message ID | 20221027040346.1104204-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 228ebc41dfab5b5d34cd76835ddb0ca8ee12f513 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] net: do not sense pfmemalloc status in skb_append_pagefrags() | expand |
Hello: This patch was applied to netdev/net.git (master) by Jakub Kicinski <kuba@kernel.org>: On Thu, 27 Oct 2022 04:03:46 +0000 you wrote: > skb_append_pagefrags() is used by af_unix and udp sendpage() > implementation so far. > > In commit 326140063946 ("tcp: TX zerocopy should not sense > pfmemalloc status") we explained why we should not sense > pfmemalloc status for pages owned by user space. > > [...] Here is the summary with links: - [net] net: do not sense pfmemalloc status in skb_append_pagefrags() https://git.kernel.org/netdev/net/c/228ebc41dfab You are awesome, thank you!
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 1d9719e72f9d9ea6ca40979ff3ba95afec4f5b37..d1a3fa6f3f1265497c0a65f8b958c6312f5f0663 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3971,7 +3971,7 @@ int skb_append_pagefrags(struct sk_buff *skb, struct page *page, } else if (i < MAX_SKB_FRAGS) { skb_zcopy_downgrade_managed(skb); get_page(page); - skb_fill_page_desc(skb, i, page, offset, size); + skb_fill_page_desc_noacc(skb, i, page, offset, size); } else { return -EMSGSIZE; }
skb_append_pagefrags() is used by af_unix and udp sendpage() implementation so far. In commit 326140063946 ("tcp: TX zerocopy should not sense pfmemalloc status") we explained why we should not sense pfmemalloc status for pages owned by user space. We should also use skb_fill_page_desc_noacc() in skb_append_pagefrags() to avoid following KCSAN report: BUG: KCSAN: data-race in lru_add_fn / skb_append_pagefrags write to 0xffffea00058fc1c8 of 8 bytes by task 17319 on cpu 0: __list_add include/linux/list.h:73 [inline] list_add include/linux/list.h:88 [inline] lruvec_add_folio include/linux/mm_inline.h:323 [inline] lru_add_fn+0x327/0x410 mm/swap.c:228 folio_batch_move_lru+0x1e1/0x2a0 mm/swap.c:246 lru_add_drain_cpu+0x73/0x250 mm/swap.c:669 lru_add_drain+0x21/0x60 mm/swap.c:773 free_pages_and_swap_cache+0x16/0x70 mm/swap_state.c:311 tlb_batch_pages_flush mm/mmu_gather.c:59 [inline] tlb_flush_mmu_free mm/mmu_gather.c:256 [inline] tlb_flush_mmu+0x5b2/0x640 mm/mmu_gather.c:263 tlb_finish_mmu+0x86/0x100 mm/mmu_gather.c:363 exit_mmap+0x190/0x4d0 mm/mmap.c:3098 __mmput+0x27/0x1b0 kernel/fork.c:1185 mmput+0x3d/0x50 kernel/fork.c:1207 copy_process+0x19fc/0x2100 kernel/fork.c:2518 kernel_clone+0x166/0x550 kernel/fork.c:2671 __do_sys_clone kernel/fork.c:2812 [inline] __se_sys_clone kernel/fork.c:2796 [inline] __x64_sys_clone+0xc3/0xf0 kernel/fork.c:2796 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd read to 0xffffea00058fc1c8 of 8 bytes by task 17325 on cpu 1: page_is_pfmemalloc include/linux/mm.h:1817 [inline] __skb_fill_page_desc include/linux/skbuff.h:2432 [inline] skb_fill_page_desc include/linux/skbuff.h:2453 [inline] skb_append_pagefrags+0x210/0x600 net/core/skbuff.c:3974 unix_stream_sendpage+0x45e/0x990 net/unix/af_unix.c:2338 kernel_sendpage+0x184/0x300 net/socket.c:3561 sock_sendpage+0x5a/0x70 net/socket.c:1054 pipe_to_sendpage+0x128/0x160 fs/splice.c:361 splice_from_pipe_feed fs/splice.c:415 [inline] __splice_from_pipe+0x222/0x4d0 fs/splice.c:559 splice_from_pipe fs/splice.c:594 [inline] generic_splice_sendpage+0x89/0xc0 fs/splice.c:743 do_splice_from fs/splice.c:764 [inline] direct_splice_actor+0x80/0xa0 fs/splice.c:931 splice_direct_to_actor+0x305/0x620 fs/splice.c:886 do_splice_direct+0xfb/0x180 fs/splice.c:974 do_sendfile+0x3bf/0x910 fs/read_write.c:1255 __do_sys_sendfile64 fs/read_write.c:1323 [inline] __se_sys_sendfile64 fs/read_write.c:1309 [inline] __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1309 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd value changed: 0x0000000000000000 -> 0xffffea00058fc188 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 17325 Comm: syz-executor.0 Not tainted 6.1.0-rc1-syzkaller-00158-g440b7895c990-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022 Fixes: 326140063946 ("tcp: TX zerocopy should not sense pfmemalloc status") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> --- net/core/skbuff.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)