On Wed, Oct 17, 2012 at 1:42 AM, Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > (2012/10/17 14:24), David Rientjes wrote: >> >> On Wed, 17 Oct 2012, Dave Jones wrote: >> >>> BUG: sleeping function called from invalid context at kernel/mutex.c:269 >>> in_atomic(): 1, irqs_disabled(): 0, pid: 8558, name: trinity-child2 >>> 3 locks on stack by trinity-child2/8558: >>> #0: held: (&p->lock){+.+.+.}, instance: ffff88010c9a00b0, at: >>> [<ffffffff8120cd1f>] seq_lseek+0x3f/0x120 >>> #1: held: (&mm->mmap_sem){++++++}, instance: ffff88013956f7c8, at: >>> [<ffffffff81254437>] m_start+0xa7/0x190 >>> #2: held: (&(&p->alloc_lock)->rlock){+.+...}, instance: >>> ffff88011fc64f30, at: [<ffffffff81254f8f>] show_numa_map+0x14f/0x610 >>> Pid: 8558, comm: trinity-child2 Not tainted 3.7.0-rc1+ #32 >>> Call Trace: >>> [<ffffffff810ae4ec>] __might_sleep+0x14c/0x200 >>> [<ffffffff816bdf4e>] mutex_lock_nested+0x2e/0x50 >>> [<ffffffff811c43a3>] mpol_shared_policy_lookup+0x33/0x90 >>> [<ffffffff8118d5c3>] shmem_get_policy+0x33/0x40 >>> [<ffffffff811c31fa>] get_vma_policy+0x3a/0x90 >>> [<ffffffff81254fa3>] show_numa_map+0x163/0x610 >>> [<ffffffff81255b10>] ? pid_maps_open+0x20/0x20 >>> [<ffffffff81255980>] ? pagemap_hugetlb_range+0xf0/0xf0 >>> [<ffffffff81255483>] show_pid_numa_map+0x13/0x20 >>> [<ffffffff8120c902>] traverse+0xf2/0x230 >>> [<ffffffff8120cd8b>] seq_lseek+0xab/0x120 >>> [<ffffffff811e6c0b>] sys_lseek+0x7b/0xb0 >>> [<ffffffff816ca088>] tracesys+0xe1/0xe6 >>> >> >> Hmm, looks like we need to change the refcount semantics entirely. We'll >> need to make get_vma_policy() always take a reference and then drop it >> accordingly. This work sif get_vma_policy() can grab a reference while >> holding task_lock() for the task policy fallback case. >> >> Comments on this approach? > > > I think this refcounting is better than using task_lock(). I don't think so. get_vma_policy() is used from fast path. In other words, number of atomic ops is sensible for allocation performance. Instead, I'd like to use spinlock for shared mempolicy instead of mutex. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>