** Description changed:

- This issue is 100% reproducible. It looks like this has something to do
- with the Disco kernel in proposed (5.0.0-1014.14).
+ [Impact]
+ ftrace test in ubuntu_kernel_selftests causes a system crash + reboot when 
testing "Register/unregister many kprobe events".
+ 
+ [Fix]
+ The issue has been discussed in the following LKML thread:
+ https://lkml.org/lkml/2019/6/5/274
+ 
+ and the following 3 upstream commits have been identified to resolve
+ this issue:
+ 
+ d2a68c4effd8 x86/ftrace: Do not call function graph from dynamic trampolines
+ 3c0dab44e227 x86/ftrace: Set trampoline pages as executable
+ 7298e24f9042 x86/kprobes: Set instruction page as executable
+ 
+ From these commits, the Disco kernel currently in -proposed
+ (5.0.0-26.27) is missing only the following commit, which has been
+ already committed as part of LP: #1839887 (Disco update: upstream stable
+ patchset 2019-08-12) but not yet released:
+ 
+ 7298e24f9042 x86/kprobes: Set instruction page as executable
+ 
+ [Regression potential]
+ The commit touches the x86/kprobes code so there's a chance of regression 
there which I would flag as medium. However, it has been applied upstream for 
v5.2-rc1 and there is no follow-up commits marked as fix for it. 
+ 
+ ----------------------------------------------
+ This issue is 100% reproducible. It looks like this has something to do with 
the Disco kernel in proposed (5.0.0-1014.14).
  
  Test combinations:
  kernel in updates + source code master branch = OK
  kernel in proposed + source code master-next branch = NOT OK
  kernel in proposed + source code master branch = NOT OK
  
  The system will crash and reboot itself when testing:
  "Register/unregister many kprobe events"
  
  [33] Kprobe event with comm arguments [PASS]
  [34] Kprobe event string type argument        [PASS]
  [35] Kprobe event symbol argument     [PASS]
  [36] Kprobe event argument syntax     [PASS]
  [37] Kprobes event arguments with types       [PASS]
  [38] Kprobe event auto/manual naming  [PASS]
  [39] Kprobe dynamic event with function tracer        [PASS]
  [40] Kretprobe dynamic event with arguments   [PASS]
  [41] Kretprobe dynamic event with maxactive   [PASS]
  [42] Register/unregister many kprobe events
  packet_write_wait: Connection to 35.233.208.253 port 22: Broken pipe
  
  Tried with use "tail -f /var/log/syslog" and "dmesg -w" to see what
  happened, but it will just disconnected and reboot itself.
  
- 
  ProblemType: Bug
  DistroRelease: Ubuntu 19.04
  Package: linux-image-5.0.0-1014-gcp 5.0.0-1014.14
  ProcVersionSignature: Ubuntu 5.0.0-1014.14-gcp 5.0.21
  Uname: Linux 5.0.0-1014-gcp x86_64
  ApportVersion: 2.20.10-0ubuntu27.1
  Architecture: amd64
  Date: Tue Aug 20 08:13:13 2019
  SourcePackage: linux-signed-gcp
  UpgradeStatus: No upgrade log present (probably fresh install)

** Changed in: linux (Ubuntu Disco)
       Status: Confirmed => In Progress

-- 
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https://bugs.launchpad.net/bugs/1840750

Title:
  [Potential Regression] System crashes when running ftrace test in
  ubuntu_kernel_selftests

Status in ubuntu-kernel-tests:
  New
Status in linux package in Ubuntu:
  Confirmed
Status in linux source package in Disco:
  In Progress

Bug description:
  [Impact]
  ftrace test in ubuntu_kernel_selftests causes a system crash + reboot when 
testing "Register/unregister many kprobe events".

  [Fix]
  The issue has been discussed in the following LKML thread:
  https://lkml.org/lkml/2019/6/5/274

  and the following 3 upstream commits have been identified to resolve
  this issue:

  d2a68c4effd8 x86/ftrace: Do not call function graph from dynamic trampolines
  3c0dab44e227 x86/ftrace: Set trampoline pages as executable
  7298e24f9042 x86/kprobes: Set instruction page as executable

  From these commits, the Disco kernel currently in -proposed
  (5.0.0-26.27) is missing only the following commit, which has been
  already committed as part of LP: #1839887 (Disco update: upstream
  stable patchset 2019-08-12) but not yet released:

  7298e24f9042 x86/kprobes: Set instruction page as executable

  [Regression potential]
  The commit touches the x86/kprobes code so there's a chance of regression 
there which I would flag as medium. However, it has been applied upstream for 
v5.2-rc1 and there is no follow-up commits marked as fix for it. 

  ----------------------------------------------
  This issue is 100% reproducible. It looks like this has something to do with 
the Disco kernel in proposed (5.0.0-1014.14).

  Test combinations:
  kernel in updates + source code master branch = OK
  kernel in proposed + source code master-next branch = NOT OK
  kernel in proposed + source code master branch = NOT OK

  The system will crash and reboot itself when testing:
  "Register/unregister many kprobe events"

  [33] Kprobe event with comm arguments [PASS]
  [34] Kprobe event string type argument        [PASS]
  [35] Kprobe event symbol argument     [PASS]
  [36] Kprobe event argument syntax     [PASS]
  [37] Kprobes event arguments with types       [PASS]
  [38] Kprobe event auto/manual naming  [PASS]
  [39] Kprobe dynamic event with function tracer        [PASS]
  [40] Kretprobe dynamic event with arguments   [PASS]
  [41] Kretprobe dynamic event with maxactive   [PASS]
  [42] Register/unregister many kprobe events
  packet_write_wait: Connection to 35.233.208.253 port 22: Broken pipe

  Tried with use "tail -f /var/log/syslog" and "dmesg -w" to see what
  happened, but it will just disconnected and reboot itself.

  ProblemType: Bug
  DistroRelease: Ubuntu 19.04
  Package: linux-image-5.0.0-1014-gcp 5.0.0-1014.14
  ProcVersionSignature: Ubuntu 5.0.0-1014.14-gcp 5.0.21
  Uname: Linux 5.0.0-1014-gcp x86_64
  ApportVersion: 2.20.10-0ubuntu27.1
  Architecture: amd64
  Date: Tue Aug 20 08:13:13 2019
  SourcePackage: linux-signed-gcp
  UpgradeStatus: No upgrade log present (probably fresh install)

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