On 2024/9/10 9:58, Miaohe Lin wrote:
On 2024/9/6 10:42, Kefeng Wang wrote:Like commit a873dfe1032a ("mm, hwpoison: try to recover from copy-on write faults"), there is another path which could crash because it does not have recovery code where poison is consumed by the kernel in do_cow_fault(), a crash calltrace shown below on old kernel, but it could be happened in the lastest mainline code, CPU: 7 PID: 3248 Comm: mpi Kdump: loaded Tainted: G OE 5.10.0 #1 pc : copy_page+0xc/0xbc lr : copy_user_highpage+0x50/0x9c Call trace: copy_page+0xc/0xbc do_cow_fault+0x118/0x2bc do_fault+0x40/0x1a4 handle_pte_fault+0x154/0x230 __handle_mm_fault+0x1a8/0x38c handle_mm_fault+0xf0/0x250 do_page_fault+0x184/0x454 do_translation_fault+0xac/0xd4 do_mem_abort+0x44/0xbc Fix it by using copy_mc_user_highpage() to handle this case and return VM_FAULT_HWPOISON for cow fault. Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> --- mm/memory.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index 42674c0748cb..d310c073a1b3 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5089,7 +5089,10 @@ static vm_fault_t do_cow_fault(struct vm_fault *vmf) if (ret & VM_FAULT_DONE_COW) return ret;- copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);+ if (copy_mc_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma)) { + ret = VM_FAULT_HWPOISON; + goto uncharge_out; + }When copy_mc_user_highpage fails, we should have vmf->page locked and hold the extra refcnt of vmf->page. So we should call unlock_page(vmf->page) and put_page(vmf->page) before goto uncharge_out?
Right, for upstream, we need to more handling for vmf->page, will fix, thanks.
Thanks. .
