Cpuset: cant mmput inside tasklist_lock fix
PATCH 1/1 Cpuset: cant mmput inside tasklist_lock fix
mmput() inside tasklist_lock() can deadlock (thanks, Andrew).
To fix, move the range check before getting the mm, so the mm doesn't have to be mmput if the check failed.
Also the BUG() was excessively cruel (panics) for this case. Even though "it can't happen", still it is easy to carry on and keep the kernel healthy, at the penalty of not placing memory exactly where the user expected.
Signed-off-by Paul Jackson <[email protected]>
---
kernel/cpuset.c | 14 +++++--------- 1 files changed, 5 insertions(+), 9 deletions(-)
kernel/cpuset.c +5 -9
@@ -881,20 +881,16 @@ static int update_nodemask(struct cpuset do_each_thread(g, p) {struct mm_struct *mm; +if (n >= ntasks) { +printk (KERN_WARNING +"Cpuset mempolicy rebind incomplete.\n" ); +continue ; + }if (p->cpuset != cs)continue ; mm =get_task_mm (p);if (!mm)continue ; -if (n >= ntasks) { -if (printk_ratelimit ()) { -printk (KERN_ERR -"Cpuset mempolicy rebind failed.\n" ); -BUG (); - } -mmput (mm); -continue ; - } mmarray[n++] = mm; }while_each_thread (g, p);write_unlock_irq (&tasklist_lock);
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Paul Jackson <[email protected]> 1.650.933.1373