On Tue, 24 Jul 2007 02:04:46 +0400 Alexey Dobriyan <[EMAIL PROTECTED]> wrote:
> On Mon, Jul 23, 2007 at 02:11:37PM -0700, Andrew Morton wrote: > > On Tue, 24 Jul 2007 01:01:53 +0400 > > Alexey Dobriyan <[EMAIL PROTECTED]> wrote: > > > > > On Tue, Jul 24, 2007 at 12:40:45AM +0400, Alexey Dobriyan wrote: > > > > > I had more complete info: > > > > > http://article.gmane.org/gmane.linux.network/66966 > > > > > > > > > > You're using DEBUG_PAGEALLOC, but I was not, so I think we can rule > > > > > that out. > > > > > > > > > > I haven't worked out where that kmap_atomic() call is coming from > > > > > yet. > > > > > Both traces point up into the page allocator, but I _think_ that's > > > > > stack > > > > > gunk. > > > > > > > > Ahh, you suspect networking. > > > > > > > > Here, setup is 2 cheap-ass 100Mb realtek 8139 NICs, one to campus > > > > network > > > > receiving ~20 junk packets per second, one gathering netconsole output > > > > and ssh to it, no conntracks and fancy stuff. > > > > > > > > [reboots with cables physically unplugged] > > > > > > OK, I run gdb recompile, cat(1) every file in /usr/portage (shitload of > > > small files) with both cables unplugged. It all went fine for ~5 minutes > > > after that it crashed exactly same way after 10 secs after plugging one > > > of them. > > > > It'd be nice to get a clean trace. Are you able to obtain the full > > trace with CONFIG_FRAME_POINTER=y? > > Sorry, no camera shot, finding camera requires wakening up M. :) > > It took longer that usual, but here it is > > kmap_atomic > get_page_from_freelist > __alloc_pages > cache_alloc_refill > __alloc_pages > cache_alloc_refill > kmem_cache_alloc > dst_alloc > ip_route_input > ip_rcv > netif_receive_skb > rtl8139_poll > net_rx_action > __do_softirq > do_softirq > irq_exit > do_IRQ > common_interrupt > handle_mm_fault > do_page_fault > error_core > > much more loaded x86_64 box near also running 2.6.23-rc1 with debugging > turned on, using atl1 driver doesn't experience any crashes. > > And I found 2.6.22-b91cba52e9b7b3f1c0037908a192d93a869ca9e5-x entry on > top of grub config which means b91cba52e9b7b3f1c0037908a192d93a869ca9e5 > _without_ any debugging was OK. I worked out that the crash I saw was in BUG_ON(!pte_none(*(kmap_pte-idx))); in the read of kmap_pte[idx]. Which would be weird as the caller is using a literal KM_USER0. So maybe I goofed, and that BUG_ON is triggering (it scrolled off, and I am unable to reproduce it now). If that BUG_ON _is_ triggering then it might indicate that someone is doing a __GFP_HIGHMEM|__GFP_ZERO allocation while holding KM_USER0. If they're holding an atomic kmap then they'll be running in_atomic so it is unlikely that they accidentally added __GFP_WAIT because lots of people would be getting lots of might_sleep() warnings. Hence that first VM_BUG_ON in prep_zero_page() _should_ be triggering. Do you have CONFIG_DEBUG_VM enabled? Also, it might be useful to apply -mm's kmap_atomic-debugging.patch. it will detect lots of abuse. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
