On 2022/4/27 17:44, Xu Yu wrote: > Kernel panic when injecting memory_failure for the global > huge_zero_page, when CONFIG_DEBUG_VM is enabled, as follows. > > Injecting memory failure for pfn 0x109ff9 at process virtual address 0x20ff9000 > page:00000000fb053fc3 refcount:2 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x109e00 > head:00000000fb053fc3 order:9 compound_mapcount:0 compound_pincount:0 > flags: 0x17fffc000010001(locked|head|node=0|zone=2|lastcpupid=0x1ffff) > raw: 017fffc000010001 0000000000000000 dead000000000122 0000000000000000 > raw: 0000000000000000 0000000000000000 00000002ffffffff 0000000000000000 > page dumped because: VM_BUG_ON_PAGE(is_huge_zero_page(head)) > ------------[ cut here ]------------ > kernel BUG at mm/huge_memory.c:2499! > invalid opcode: 0000 [#1] PREEMPT SMP PTI > CPU: 6 PID: 553 Comm: split_bug Not tainted 5.18.0-rc1+ #11 > Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 3288b3c 04/01/2014 > RIP: 0010:split_huge_page_to_list+0x66a/0x880 > Code: 84 9b fb ff ff 48 8b 7c 24 08 31 f6 e8 9f 5d 2a 00 b8 b8 02 00 00 e9 e8 fb ff ff 48 c7 c6 e8 47 3c 82 4c b > RSP: 0018:ffffc90000dcbdf8 EFLAGS: 00010246 > RAX: 000000000000003c RBX: 0000000000000001 RCX: 0000000000000000 > RDX: 0000000000000000 RSI: ffffffff823e4c4f RDI: 00000000ffffffff > RBP: ffff88843fffdb40 R08: 0000000000000000 R09: 00000000fffeffff > R10: ffffc90000dcbc48 R11: ffffffff82d68448 R12: ffffea0004278000 > R13: ffffffff823c6203 R14: 0000000000109ff9 R15: ffffea000427fe40 > FS: 00007fc375a26740(0000) GS:ffff88842fd80000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fc3757c9290 CR3: 0000000102174006 CR4: 00000000003706e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > try_to_split_thp_page+0x3a/0x130 > memory_failure+0x128/0x800 > madvise_inject_error.cold+0x8b/0xa1 > __x64_sys_madvise+0x54/0x60 > do_syscall_64+0x35/0x80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > RIP: 0033:0x7fc3754f8bf9 > Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 8 > RSP: 002b:00007ffeda93a1d8 EFLAGS: 00000217 ORIG_RAX: 000000000000001c > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc3754f8bf9 > RDX: 0000000000000064 RSI: 0000000000003000 RDI: 0000000020ff9000 > RBP: 00007ffeda93a200 R08: 0000000000000000 R09: 0000000000000000 > R10: 00000000ffffffff R11: 0000000000000217 R12: 0000000000400490 > R13: 00007ffeda93a2e0 R14: 0000000000000000 R15: 0000000000000000 > > We think that raising BUG is overkilling for splitting huge_zero_page, > the huge_zero_page can't be met from normal paths other than memory > failure, but memory failure is a valid caller. So we tend to replace the > BUG to WARN + returning -EBUSY, and thus the panic above won't happen > again. > > Suggested-by: Yang Shi <shy828301@xxxxxxxxx> > Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx> > Reported-by: kernel test robot <lkp@xxxxxxxxx> > Signed-off-by: Xu Yu <xuyu@xxxxxxxxxxxxxxxxx> LGTM. Thanks! Reviewed-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> > --- > mm/huge_memory.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index c468fee595ff..910a138e9859 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2495,11 +2495,16 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) > struct address_space *mapping = NULL; > int extra_pins, ret; > pgoff_t end; > + bool is_hzp; > > - VM_BUG_ON_PAGE(is_huge_zero_page(head), head); > VM_BUG_ON_PAGE(!PageLocked(head), head); > VM_BUG_ON_PAGE(!PageCompound(head), head); > > + is_hzp = is_huge_zero_page(head); > + VM_WARN_ON_ONCE_PAGE(is_hzp, head); > + if (is_hzp) > + return -EBUSY; > + > if (PageWriteback(head)) > return -EBUSY; > >
