Message ID | 20090415174658.AC4F.A69D9226@jp.fujitsu.com |
---|---|
State | Not Applicable, archived |
Delegated to: | David Miller |
Headers | show |
KOSAKI Motohiro wrote: >>> I would perhaps not fold gup_fast conversions into the same patch as >>> the fix. >> >> OK. I'll fix. > > Done. > > > > =================================== > Subject: [Untested][RFC][PATCH] fix wrong get_user_pages usage in iovlock.c > > down_read(mmap_sem) > get_user_pages() > up_read(mmap_sem) > > is fork unsafe. > fix it. > > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> > Cc: Maciej Sosnowski <maciej.sosnowski@intel.com> > Cc: David S. Miller <davem@davemloft.net> > Cc: Chris Leech <christopher.leech@intel.com> > Cc: netdev@vger.kernel.org > --- > drivers/dma/iovlock.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > Index: b/drivers/dma/iovlock.c > =================================================================== > --- a/drivers/dma/iovlock.c 2009-04-13 22:58:36.000000000 +0900 > +++ b/drivers/dma/iovlock.c 2009-04-14 20:27:16.000000000 +0900 > @@ -104,8 +104,6 @@ struct dma_pinned_list *dma_pin_iovec_pa > 0, /* force */ > page_list->pages, > NULL); > - up_read(¤t->mm->mmap_sem); > - > if (ret != page_list->nr_pages) > goto unpin; > > @@ -127,6 +125,8 @@ void dma_unpin_iovec_pages(struct dma_pi > if (!pinned_list) > return; > > + up_read(¤t->mm->mmap_sem); > + > for (i = 0; i < pinned_list->nr_iovecs; i++) { > struct dma_page_list *page_list = &pinned_list->page_list[i]; > for (j = 0; j < page_list->nr_pages; j++) { I have tried it with net_dma and here is what I've got. Regards, Maciej --- ======================================================= [ INFO: possible circular locking dependency detected ] 2.6.30-rc2 #2 ------------------------------------------------------- iperf/10555 is trying to acquire lock: (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff80450991>] sk_wait_data+0x90/0xc5 but task is already holding lock: (&mm->mmap_sem){++++++}, at: [<ffffffff8043d0f6>] dma_pin_iovec_pages+0x122/0x1a0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&mm->mmap_sem){++++++}: [<ffffffffffffffff>] 0xffffffffffffffff -> #0 (sk_lock-AF_INET){+.+.+.}: [<ffffffffffffffff>] 0xffffffffffffffff other info that might help us debug this: 1 lock held by iperf/10555: #0: (&mm->mmap_sem){++++++}, at: [<ffffffff8043d0f6>] dma_pin_iovec_pages+0x122/0x1a0 stack backtrace: Pid: 10555, comm: iperf Tainted: G W 2.6.30-rc2 #2 Call Trace: [<ffffffff8025b1dc>] ? print_circular_bug_tail+0xc0/0xc9 [<ffffffff8025aa2b>] ? print_circular_bug_header+0xc8/0xcf [<ffffffff8025b984>] ? validate_chain+0x67d/0xc7c [<ffffffff8025c6e6>] ? __lock_acquire+0x763/0x7ec [<ffffffff8025c835>] ? lock_acquire+0xc6/0xea [<ffffffff80450991>] ? sk_wait_data+0x90/0xc5 [<ffffffff8044ff01>] ? lock_sock_nested+0xee/0x100 [<ffffffff80450991>] ? sk_wait_data+0x90/0xc5 [<ffffffff80259b07>] ? mark_held_locks+0x43/0x5b [<ffffffff802403ee>] ? local_bh_enable_ip+0xc4/0xc7 [<ffffffff80259c3c>] ? trace_hardirqs_on_caller+0x11d/0x148 [<ffffffff80450991>] ? sk_wait_data+0x90/0xc5 [<ffffffff8024ebb3>] ? autoremove_wake_function+0x0/0x2e [<ffffffff80488ad3>] ? tcp_recvmsg+0x3bf/0xa21 [<ffffffff8044f601>] ? sock_common_recvmsg+0x30/0x45 [<ffffffff8044d847>] ? sock_recvmsg+0xf0/0x10f [<ffffffff8024ebb3>] ? autoremove_wake_function+0x0/0x2e [<ffffffff8025c704>] ? __lock_acquire+0x781/0x7ec [<ffffffff802b553c>] ? fget_light+0xd5/0xdf [<ffffffff802b54b0>] ? fget_light+0x49/0xdf [<ffffffff8044e91b>] ? sys_recvfrom+0xbc/0x119 [<ffffffff80259c3c>] ? trace_hardirqs_on_caller+0x11d/0x148 [<ffffffff804e1a7f>] ? _spin_unlock_irq+0x24/0x27 [<ffffffff802359ab>] ? finish_task_switch+0x7a/0xe4 [<ffffffff80235967>] ? finish_task_switch+0x36/0xe4 [<ffffffff804df188>] ? thread_return+0x3e/0x97 [<ffffffff802718f7>] ? audit_syscall_entry+0x192/0x1bd [<ffffffff8020b96b>] ? system_call_fastpath+0x16/0x1b -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
=================================== Subject: [Untested][RFC][PATCH] fix wrong get_user_pages usage in iovlock.c down_read(mmap_sem) get_user_pages() up_read(mmap_sem) is fork unsafe. fix it. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Maciej Sosnowski <maciej.sosnowski@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chris Leech <christopher.leech@intel.com> Cc: netdev@vger.kernel.org --- drivers/dma/iovlock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) Index: b/drivers/dma/iovlock.c =================================================================== --- a/drivers/dma/iovlock.c 2009-04-13 22:58:36.000000000 +0900 +++ b/drivers/dma/iovlock.c 2009-04-14 20:27:16.000000000 +0900 @@ -104,8 +104,6 @@ struct dma_pinned_list *dma_pin_iovec_pa 0, /* force */ page_list->pages, NULL); - up_read(¤t->mm->mmap_sem); - if (ret != page_list->nr_pages) goto unpin; @@ -127,6 +125,8 @@ void dma_unpin_iovec_pages(struct dma_pi if (!pinned_list) return; + up_read(¤t->mm->mmap_sem); + for (i = 0; i < pinned_list->nr_iovecs; i++) { struct dma_page_list *page_list = &pinned_list->page_list[i]; for (j = 0; j < page_list->nr_pages; j++) {