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authorPaul Jackson <pj@sgi.com>2006-01-14 13:21:06 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-14 18:27:10 -0800
commit505970b96e3b7d22177c38e03435a68376628e7a (patch)
tree5508317e391961355bf3d946a6aac05bb21569eb /include/linux/cpuset.h
parented68cb3676bb179768529aeb808403d57295af56 (diff)
[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 <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux/cpuset.h')
-rw-r--r--include/linux/cpuset.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index c472f972bd6..3bc60692711 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 */