tree be6c6c4e16cfac07edf437a1f74ef027ada8ccc7
parent c1f5a1944657ba6abe375e3bb2a3238a46849f70
author Andrew Morton <akpm@osdl.org> 1143284868 -0800
committer Linus Torvalds <torvalds@g5.osdl.org> 1143303777 -0800

[PATCH] find_task_by_pid() needs tasklist_lock

A couple of places are forgetting to take it.

The kswapd case is probably unimportant.  keventd_create_kthread() was racy.

The whole thing is a bit flakey: you start a kernel thread, get its pid from
kernel_thread() then look up its task_struct.

a) It assumes that pid recycling takes a "long" time.

b) We get a task_struct but no reference was taken on it.  The owner of the
   kswapd and kthread task_struct*'s must assume that the new thread won't
   exit unexpectedly.  Because if it does, they're left holding dead memory
   and any attempt to control or stop that task will crash.

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>