lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 21 Jan 2008 15:14:45 +0300 From: Evgeniy Polyakov <johnpol@....mipt.ru> To: David Miller <davem@...emloft.net> Cc: akpm@...ux-foundation.org, xemul@...nvz.org, bugme-daemon@...zilla.kernel.org, nigel@...pend2.net, netdev@...r.kernel.org Subject: Re: [Bugme-new] [Bug 9778] New: unregister_netdevice: waiting for [device] to become free On Sun, Jan 20, 2008 at 02:30:27AM -0800, David Miller (davem@...emloft.net) wrote: > From: Andrew Morton <akpm@...ux-foundation.org> > Date: Sat, 19 Jan 2008 16:58:02 -0800 > > > ouch. > > Yep, several people are hitting this it seems. > > If Pavel doesn't provide a fix or direction soon I'll just revert. It looks like patch is still valid. Here is a problem description as I undestood. When new device (let's talk about ethernet, since that is what I tested) is being turned on, it gets neigh_parms entry allocated for it via inetdev_init(), which is called for NETDEV_REGISTER inetdev event. This entry is stored in arp_tbl table and is in_dev->arp_parms. When later new arp entry is created, device is provided into arp_constructor(), which clones (increase reference counter) device's in_dev->arp_parms and puts it into provided neighbour entry. When later we remove device, its in_dev->arp_parms's reference counter is high enough (it is equal to number of arp entries found on given device plu one), so neigh_parms_destroy() is not called. Later all neighbour entries are flushed by garbage collector and reference counter for that parm hits zero and device can be removed. I will think about how to fix the problem nicely or if this patch still can be simplified/dropped, but so far it looks valid. Maybe this analysis will help someone to fix problem first. Here is debug dmesg: [ 21.835595] inetdev_init: allocating parms. [ 21.839829] neigh_parms_alloc: parms: ffff81003d8e8df0, dev: eth0, refcnt: 1, dev_refcnt: 2. ... [ 30.251576] r8169: eth0: link up [ 31.067079] NET: Registered protocol family 10 [ 31.072055] neigh_parms_alloc: parms: ffff81003efc72a8, dev: lo, refcnt: 1, dev_refcnt: 9. [ 31.080891] neigh_alloc: parms: ffffffff8812afe8, dev: <NULL>, refcnt: 2. [ 31.087816] neigh_parms_alloc: parms: ffff81003efc7210, dev: eth0, refcnt: 1, dev_refcnt: 9. [ 31.097335] neigh_alloc: parms: ffffffff804deb88, dev: <NULL>, refcnt: 2. [ 31.104172] arp_constructor: parms: ffff81003f8c3be8, dev: lo, refcnt: 2. [ 31.500348] neigh_alloc: parms: ffffffff8812afe8, dev: <NULL>, refcnt: 2. [ 32.499628] neigh_alloc: parms: ffffffff8812afe8, dev: <NULL>, refcnt: 2. [ 102.827796] neigh_destroy: parms: ffff81003efc7210, dev: eth0, refcnt: 3, dev_refcnt: 13. [ 106.828843] neigh_destroy: parms: ffff81003f8c3be8, dev: lo, refcnt: 2, dev_refcnt: 78. [ 109.810987] neigh_alloc: parms: ffffffff804deb88, dev: <NULL>, refcnt: 2. First arp entry for eth0 device, bump the counter: [ 109.817827] arp_constructor: parms: ffff81003d8e8df0, dev: eth0, refcnt: 2. [ 109.831811] neigh_alloc: parms: ffffffff804deb88, dev: <NULL>, refcnt: 2. [ 109.838661] arp_constructor: parms: ffff81003f8c3be8, dev: lo, refcnt: 2. [ 110.837894] neigh_destroy: parms: ffff81003efc7210, dev: eth0, refcnt: 2, dev_refcnt: 15. Can not release that neigh parm: [ 113.638228] neigh_parms_release: parms: ffff81003d8e8df0, dev: eth0, refcnt: 2, dev_refcnt: 5. Can release some other (for ipv6): [ 113.649380] neigh_parms_release: parms: ffff81003efc7210, dev: eth0, refcnt: 1, dev_refcnt: 5. [ 113.671806] neigh_parms_destroy: parms: ffff81003efc7210, dev: eth0, dev_refcnt: 3. [ 123.916250] unregister_netdevice: waiting for eth0 to become free. Usage count = 1 GC hits us: [ 124.839572] neigh_destroy: parms: ffff81003d8e8df0, dev: eth0, refcnt: 1, dev_refcnt: 11. [ 124.847813] neigh_parms_destroy: parms: ffff81003d8e8df0, dev: eth0, dev_refcnt: 1. [ 124.952026] ACPI: PCI interrupt for device 0000:02:0d.0 disabled -- Evgeniy Polyakov -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists