Messages in this thread Patch in this message | | | Date | Thu, 26 May 2005 01:25:16 -0700 (PDT) | From | Paul Jackson <> | Subject | [PATCH 2.6.12-rc4] cpuset rmdir scheduling while atomic fix |
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Andrew,
This fixes a complaint that I am seeing while running a particular stress test. Please push it along at your convenience.
The cpuset kernel code can generate a "scheduling while atomic" complaint from the cpuset_rmdir code. This complaint means that we had to sleep while trying to get the cpuset_sem global semaphore during the handling of a 'rmdir()' call to remove a cpuset.
The existing code tries to take the global cpuset_sem semaphore while holding a dentry spinlock. The fix is easy enough - the code that requires cpuset_sem can be moved below the point where the dentry spinlock is released.
This bug is usually only seen when running stress tests or loads causing rapid cpuset creation and deletion and queries.
The following fix has been tested using a current -linus git kernel. Without the fix, I have a stress test that generates a scheduling while atomic complaint every few seconds. With the fix, I've seen no more complaints in several hours of the same stress test.
Signed-off-by: Paul Jackson <pj@sgi.com>
Index: 2.6-cpuset_path_fix/kernel/cpuset.c =================================================================== --- 2.6-cpuset_path_fix.orig/kernel/cpuset.c 2005-05-20 22:11:48.000000000 -0700 +++ 2.6-cpuset_path_fix/kernel/cpuset.c 2005-05-20 22:12:15.000000000 -0700 @@ -1320,11 +1320,11 @@ static int cpuset_rmdir(struct inode *un parent = cs->parent; set_bit(CS_REMOVED, &cs->flags); list_del(&cs->sibling); /* delete my sibling from parent->children */ - if (list_empty(&parent->children)) - check_for_release(parent); d = dget(cs->dentry); cs->dentry = NULL; spin_unlock(&d->d_lock); + if (list_empty(&parent->children)) + check_for_release(parent); cpuset_d_remove_dir(d); dput(d); up(&cpuset_sem); -- -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson <pj@sgi.com> 1.650.933.1373 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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