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mm: migrate: simplify find_mm_struct()

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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: Nanyong Sun <sunnanyong@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Nanyong Sun 2024-09-05 23:31:18 +08:00 committed by Andrew Morton
parent 25e8acbcf1
commit 46dcc7c92e
1 changed files with 1 additions and 7 deletions
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8
mm/migrate.c
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@ -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))