From: Anton Vorontsov Date: Thu, 31 May 2012 23:26:24 +0000 (-0700) Subject: blackfin: a couple of task->mm handling fixes X-Git-Tag: v3.5-rc1~21^2~33 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2214f707de257c35773d5cd68cec9e31b91e01ca;p=pandora-kernel.git blackfin: a couple of task->mm handling fixes The patch fixes two problems: 1. Working with task->mm w/o getting mm or grabing the task lock is dangerous as ->mm might disappear (exit_mm() assigns NULL under task_lock(), so tasklist lock is not enough). We can't use get_task_mm()/mmput() pair as mmput() might sleep, so we have to take the task lock while handle its mm. 2. Checking for process->mm is not enough because process' main thread may exit or detach its mm via use_mm(), but other threads may still have a valid mm. To catch this we use find_lock_task_mm(), which walks up all threads and returns an appropriate task (with task lock held). Suggested-by: Oleg Nesterov Signed-off-by: Anton Vorontsov Cc: Mike Frysinger Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed