The patch titled
Subject: mm: migrate: simplify find_mm_struct()
has been added to the -mm mm-unstable branch. Its filename is
mm-migrate-simplify-find_mm_struct.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-migrate-simplify-find_mm_struct.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Nanyong Sun <sunnanyong@xxxxxxxxxx>
Subject: mm: migrate: simplify find_mm_struct()
Date: Thu, 5 Sep 2024 23:31:18 +0800
Use find_get_task_by_vpid() to replace the task_struct find logic in
find_mm_struct(), note that this patch move the ptrace_may_access() call
out from rcu_read_lock() scope, this is ok because it actually does not
need it, find_get_task_by_vpid() already get the pid and task safely,
ptrace_may_access() can use the task safely, like what
sched_core_share_pid() similarly do.
Link: https://lkml.kernel.org/r/20240905153118.1205173-1-sunnanyong@xxxxxxxxxx
Signed-off-by: Nanyong Sun <sunnanyong@xxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
--- a/mm/migrate.c~mm-migrate-simplify-find_mm_struct
+++ a/mm/migrate.c
@@ -2505,25 +2505,19 @@ static struct mm_struct *find_mm_struct(
return current->mm;
}
- /* Find the mm_struct */
- rcu_read_lock();
- task = find_task_by_vpid(pid);
+ task = find_get_task_by_vpid(pid);
if (!task) {
- rcu_read_unlock();
return ERR_PTR(-ESRCH);
}
- get_task_struct(task);
/*
* Check if this process has the right to modify the specified
* process. Use the regular "ptrace_may_access()" checks.
*/
if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
- rcu_read_unlock();
mm = ERR_PTR(-EPERM);
goto out;
}
- rcu_read_unlock();
mm = ERR_PTR(security_task_movememory(task));
if (IS_ERR(mm))
_
Patches currently in -mm which might be from sunnanyong@xxxxxxxxxx are
mm-migrate-simplify-find_mm_struct.patch
