linux-kernel - [PATCH 2/2] uprobes: is_trap_at_addr: don't use get_user_pages

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Message-ID: <20240710140108.GB1084@redhat.com>
Date: Wed, 10 Jul 2024 16:01:08 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: andrii@...nel.org, mhiramat@...nel.org, peterz@...radead.org
Cc: clm@...a.com, jolsa@...nel.org, mingo@...nel.org, paulmck@...nel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] uprobes: is_trap_at_addr: don't use
 get_user_pages_remote()

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@...nel.org>
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 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