From 505970b96e3b7d22177c38e03435a68376628e7a Mon Sep 17 00:00:00 2001 From: Paul Jackson Date: Sat, 14 Jan 2006 13:21:06 -0800 Subject: [PATCH] cpuset oom lock fix The problem, reported in: http://bugzilla.kernel.org/show_bug.cgi?id=5859 and by various other email messages and lkml posts is that the cpuset hook in the oom (out of memory) code can try to take a cpuset semaphore while holding the tasklist_lock (a spinlock). One must not sleep while holding a spinlock. The fix seems easy enough - move the cpuset semaphore region outside the tasklist_lock region. This required a few lines of mechanism to implement. The oom code where the locking needs to be changed does not have access to the cpuset locks, which are internal to kernel/cpuset.c only. So I provided a couple more cpuset interface routines, available to the rest of the kernel, which simple take and drop the lock needed here (cpusets callback_sem). Signed-off-by: Paul Jackson Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/cpuset.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index c472f972bd6d..3bc606927116 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -48,6 +48,9 @@ extern void __cpuset_memory_pressure_bump(void); extern struct file_operations proc_cpuset_operations; extern char *cpuset_task_status_allowed(struct task_struct *task, char *buffer); +extern void cpuset_lock(void); +extern void cpuset_unlock(void); + #else /* !CONFIG_CPUSETS */ static inline int cpuset_init_early(void) { return 0; } @@ -93,6 +96,9 @@ static inline char *cpuset_task_status_allowed(struct task_struct *task, return buffer; } +static inline void cpuset_lock(void) {} +static inline void cpuset_unlock(void) {} + #endif /* !CONFIG_CPUSETS */ #endif /* _LINUX_CPUSET_H */ -- cgit v1.2.2