Bug 14412

Summary: ltp test hangs when mounting loopback
Product: [QA/Testing] Runtime Testing Reporter: Alexandre Belloni <alexandre.belloni>
Component: generalAssignee: Bruce Ashfield <bruce.ashfield>
Status: RESOLVED FIXED QA Contact:
Severity: normal    
Priority: Medium+ CC: randy.macleod, richard.purdie
Version: unspecified   
Target Milestone: 3.4 M2   
Hardware: x86   
OS: Multiple   
Whiteboard: AB-INT AB-INT-TMPFS
OS type for building Yocto: --- Type of Regression: ---
Verified: Documentation change: No (bug/feature does not impact docs)

Description Alexandre Belloni 2021-05-29 22:28:00 UTC 
https://autobuilder.yoctoproject.org/typhoon/#/builders/95/builds/1948/steps/12/logs/stdio

Not apparent at all in the logs and probably the cause of some issues reported in bug 13802.

When mounting on of the loopback devices, the kernel oopses:

[ 2131.423042] BUG: kernel NULL pointer dereference, address: 0000000000000008
[ 2131.444555]  ? show_vfsmnt+0x1b1/0x200
[ 2131.444943]  m_show+0x1a/0x20
[ 2131.445274]  seq_read_iter+0x2c8/0x490
[ 2131.445689]  new_sync_read+0x10d/0x190
[ 2131.446078]  vfs_read+0x128/0x180
[ 2131.446445]  ksys_read+0x67/0xe0
[ 2131.446798]  __x64_sys_read+0x19/0x20
[ 2131.447199]  do_syscall_64+0x38/0x50
[ 2131.447596]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

[ 2131.473108] BUG: kernel NULL pointer dereference, address: 0000000000000008
[ 2131.493140] Call Trace:
[ 2131.493401]  show_mountinfo+0x8b/0x330
[ 2131.493799]  m_show+0x1a/0x20
[ 2131.494108]  seq_read_iter+0x2c8/0x490
[ 2131.494494]  new_sync_read+0x10d/0x190
[ 2131.494880]  vfs_read+0x128/0x180
[ 2131.495228]  ksys_read+0x67/0xe0
[ 2131.495562]  __x64_sys_read+0x19/0x20
[ 2131.495941]  do_syscall_64+0x38/0x50
[ 2131.496312]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

See https://lists.yoctoproject.org/g/swat/topic/further_ltp_hang_kernel/83025674
Comment 1 Randy MacLeod 2021-06-03 14:39:24 UTC 
Alex is going to add more info but it seems like a kernel bug.
Comment 2 Bruce Ashfield 2021-06-03 14:58:45 UTC 
I'm unfortunately not going to be looking into this any time soon, so putting me in as the assignee, will mean it sits just as long.
Comment 3 Alexandre Belloni 2021-06-10 13:19:25 UTC 
From RP:

http://git.yoctoproject.org/cgit.cgi/poky-contrib/commit/?h=rpurdie/t222&id=d7d65aae104caa03afc28837b0abe0b486d5a8b8

IMAGE_INSTALL_append = ' ltp'
TEST_SUITES = 'ping ssh ltp'
then bitbake core-image-sato; bitbake core-image-sato -c testimage 

Look for BUG: in log in core-image-sato WORKDIR/testimage/qemu*