For THPs page_check_address() always fails. It leads to endless loop in
uprobe_write_opcode().
Testcase with huge-tmpfs (not sure if it's possible to trigger this
uprobe codepath for anon memory):
mount -t debugfs none /sys/kernel/debug
mount -t tmpfs -o huge=always none /mnt
gcc -Wall -O2 -o /mnt/test -x c - <<EOF
int main(void)
{
return 0;
}
/* Padding to map the code segment with huge pmd */
asm (".zero 2097152");
EOF
echo 'p /mnt/test:0' > /sys/kernel/debug/tracing/uprobe_events
echo 1 > /sys/kernel/debug/tracing/events/uprobes/enable
/mnt/test
Let's split THPs before trying to replace.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
kernel/events/uprobes.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index d416f3baf392..1e65c79e52a6 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -300,8 +300,8 @@ int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
retry:
/* Read the page with vaddr into memory */
- ret = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &old_page,
- &vma, NULL);
+ ret = get_user_pages_remote(NULL, mm, vaddr, 1,
+ FOLL_FORCE | FOLL_SPLIT, &old_page, &vma, NULL);
if (ret <= 0)
return ret;
--
2.11.0
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