Commit 46dcc7c9 authored by Nanyong Sun's avatar Nanyong Sun Committed by Andrew Morton
Browse files

mm: migrate: simplify find_mm_struct() 

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@huawei.com


Signed-off-by: default avatarNanyong Sun <sunnanyong@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 25e8acbc

mm/migrate.c

+1 −7
Original line number Diff line number Diff line
@@ -2505,25 +2505,19 @@ static struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes) 
		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))