[PATCH 2/2] uprobes: is_trap_at_addr: don't use get_user_pages_remote()

From: Oleg Nesterov
Date: Wed Jul 10 2024 - 10:04:20 EST


get_user_pages_remote() and the comment above it make no sense.

There is no task_struct passed into get_user_pages_remote() anymore, and
nowadays mm_account_fault() increments the current->min/maj_flt counters
regardless of FAULT_FLAG_REMOTE.

Reported-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
kernel/events/uprobes.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index d52b624a50fa..1bdf386485d4 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -453,7 +453,7 @@ static int update_ref_ctr(struct uprobe *uprobe, struct mm_struct *mm,
* @vaddr: the virtual address to store the opcode.
* @opcode: opcode to be written at @vaddr.
*
- * Called with mm->mmap_lock held for read or write.
+ * Called with mm->mmap_lock held.
* Return 0 (success) or a negative errno.
*/
int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
@@ -2024,13 +2024,7 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
if (likely(result == 0))
goto out;

- /*
- * The NULL 'tsk' here ensures that any faults that occur here
- * will not be accounted to the task. 'mm' *is* current->mm,
- * but we treat this as a 'remote' access since it is
- * essentially a kernel access to the memory.
- */
- result = get_user_pages_remote(mm, vaddr, 1, FOLL_FORCE, &page, NULL);
+ result = get_user_pages(vaddr, 1, FOLL_FORCE, &page);
if (result < 0)
return result;

--
2.25.1.362.g51ebf55