On 12/5/18 4:58 AM, Greg Kroah-Hartman wrote: > On Tue, Dec 04, 2018 at 07:09:46PM -0200, Rafael David Tinoco wrote: >> On 12/4/18 8:48 AM, Greg Kroah-Hartman wrote: >>> This is the start of the stable review cycle for the 4.19.7 release. >>> There are 139 patches in this series, all will be posted as a response >>> to this one. If anyone has any issues with these being applied, please >>> let me know. >>> >>> Responses should be made by Thu Dec 6 10:36:22 UTC 2018. >>> Anything received after that time might be too late. >>> >>> The whole patch series can be found in one patch at: >>> https://www.kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.19.7-rc1.gz >>> or in the git tree and branch at: >>> git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-4.19.y >>> and the diffstat can be found below. >>> >>> thanks, >>> >>> greg k-h >> >> During functional tests for this v4.19 release, we faced a PANIC, >> described bellow, but unlikely related to this specific v4.19 version. >> >> First a WARN() at tcp_output.c: >> >> tcp_send_loss_probe(): >> ... >> /* Retransmit last segment. */ >> if (WARN_ON(!skb)) >> goto rearm_timer; >> ... >> >> [ 173.557528] WARNING: CPU: 1 PID: 0 at >> /srv/oe/build/tmp-rpb-glibc/work-shared/juno/kernel-source/net/ipv4/tcp_output.c:2485 >> tcp_send_loss_probe+0x164/0x1e8 >> [ 173.571425] Modules linked in: crc32_ce crct10dif_ce fuse >> [ 173.576804] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.7-rc1 #1 >> [ 173.583014] Hardware name: ARM Juno development board (r2) (DT) > > So only this one machine saw this failure? > > If you can reproduce it again, bisection would be great to do if > possible. Yes, the only machine... I'm afraid this issue is intermittent and depends on TCP Tail Loss and a specific race causing the NULL dereference, so bisection would be tricky since it has happened independently of the functional test that was running. I have also copied authors for the Tail Loss code to check if they got any clues even without KASAN data. Thank you, - Rafael D. Tinoco
