Most recent kernel where this bug did not occur: 2.6.13
Distribution: Ubuntu 6.04
Hardware Environment: IBM IntelliStation Z20, 2x 3.4GHz Xeons, 2G RAM, 2x 80GB
SATA disks
Software Environment: 
Problem Description: cpuset_excl_nodes_overlap() may sleep (as it takes
semaphore), but is called from atomic context - select_bad_process() under
tasklist_lock. BUG. Found by Denis Lunev.

Steps to reproduce: Run pounder2 stress tests overnight until OOM occurs, and
then watch the debug messages pour off the screen:

Debug: sleeping function called from invalid context at include/asm/semaphore.h:105
in_atomic():1, irqs_disabled():0

Call Trace:<ffffffff80130640>{__might_sleep+179}
<ffffffff8015bb68>{cpuset_excl_nodes_overlap+31}
       <ffffffff80164d9f>{out_of_memory+123} <ffffffff801676c4>{__alloc_pages+564}
       <ffffffff8017ec41>{alloc_pages_current+160}
<ffffffff8016873f>{__do_page_cache_readahead+197}
       <ffffffff8010e5c3>{__switch_to+50}
<ffffffff8031c547>{_spin_unlock_irqrestore+52}
       <ffffffff80166604>{free_pages_bulk+674}
<ffffffff80168a00>{do_page_cache_readahead+82}
       <ffffffff8016355a>{filemap_nopage+332}
<ffffffff8017378f>{__handle_mm_fault+1162}
       <ffffffff8031c547>{_spin_unlock_irqrestore+52}
<ffffffff8031df02>{do_page_fault+1096}
       <ffffffff801991ee>{sys_select+839} <ffffffff8011078d>{error_exit+0}

Eventually it becomes a never-ending stream of this:

scheduling while atomic: dd/0x00000001/510

Call Trace:<ffffffff8031a847>{schedule+122} <ffffffff8031c31f>{__down+229}
       <ffffffff80132ef7>{default_wake_function+0}
<ffffffff8031bf88>{__down_failed+53}
       <ffffffff8015cfbe>{.text.lock.cpuset+85}
<ffffffff80164d9f>{out_of_memory+123}
       <ffffffff801676c4>{__alloc_pages+564} <ffffffff8017ed26>{alloc_page_vma+221}
       <ffffffff8017ae57>{read_swap_cache_async+74}
<ffffffff801717b4>{swapin_readahead+97}
       <ffffffff8031c48c>{_read_unlock_irq+46}
<ffffffff80173a9b>{__handle_mm_fault+1942}
       <ffffffff8031c547>{_spin_unlock_irqrestore+52}
<ffffffff8031df02>{do_page_fault+1096}
       <ffffffff802050ab>{_raw_spin_trylock+8}
<ffffffff801acb0c>{inotify_dentry_parent_queue_event+136}
       <ffffffff8011078d>{error_exit+0}