[PATCH 1/2] mm: support poison recovery from do_cow_fault()

Kefeng Wang
2024-09-06T02:42:41Z

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@huawei.com>
---
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;
+ }
__folio_mark_uptodate(folio);

ret |= finish_fault(vmf);
--
2.27.0