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| Started by | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| First post | 2017-02-17 18:10 +0100 |
| Last post | 2017-02-17 20:40 +0100 |
| Articles | 3 — 2 participants |
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Re: kmemleak splat on copy_process() Andy Lutomirski <luto@amacapital.net> - 2017-02-17 18:10 +0100
Re: kmemleak splat on copy_process() "Luis R. Rodriguez" <mcgrof@kernel.org> - 2017-02-17 18:30 +0100
Re: kmemleak splat on copy_process() Andy Lutomirski <luto@amacapital.net> - 2017-02-17 20:40 +0100
| From | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| Date | 2017-02-17 18:10 +0100 |
| Subject | Re: kmemleak splat on copy_process() |
| Message-ID | <tbUcH-76j-27@gated-at.bofh.it> |
On Wed, Feb 8, 2017 at 5:37 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote: > On Tue, Feb 07, 2017 at 09:03:43AM +0100, Michal Hocko wrote: >> On Tue 07-02-17 02:37:02, Luis R. Rodriguez wrote: >> > > From a quick check I do not see any leak there either. >> > >> > Then in that case what about: >> >> This just disables the kmemleak altogether which doesn't sound like a >> good idea to me. > > Only for this case, but if that is also not desirable let us debug further. > That or I think we could perhaps massage code to make it clearer to kmemleak > things are good. > I'm not seeing the issue. There should be a live pointer to stack at all times, either in a local variable or in task->stack. There's a weird window in dup_task_struct in which we're stashing away stack_vm_area, but stack itself should be okay, I think. But maybe there really is a race in which a kmemleak check right in the middle of duplicating the task struct really can't see the stack pointer.
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| From | "Luis R. Rodriguez" <mcgrof@kernel.org> |
|---|---|
| Date | 2017-02-17 18:30 +0100 |
| Message-ID | <tbUw1-7dc-9@gated-at.bofh.it> |
| In reply to | #1583605 |
On Fri, Feb 17, 2017 at 9:07 AM, Andy Lutomirski <luto@amacapital.net> wrote: > But maybe > there really is a race in which a kmemleak check right in the middle > of duplicating the task struct really can't see the stack pointer. Funny, but it was actually using kmemleak how I can easily reproduce: To reproduce the kmemleak splat: echo clear > /sys/kernel/debug/kmemleak echo scan > /sys/kernel/debug/kmemleak cat /sys/kernel/debug/kmemleak Try that. Luis
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| From | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| Date | 2017-02-17 20:40 +0100 |
| Message-ID | <tbWxP-8rv-7@gated-at.bofh.it> |
| In reply to | #1583614 |
On Fri, Feb 17, 2017 at 9:23 AM, Luis R. Rodriguez <mcgrof@kernel.org> wrote: > On Fri, Feb 17, 2017 at 9:07 AM, Andy Lutomirski <luto@amacapital.net> wrote: >> But maybe >> there really is a race in which a kmemleak check right in the middle >> of duplicating the task struct really can't see the stack pointer. > > Funny, but it was actually using kmemleak how I can easily reproduce: > > To reproduce the kmemleak splat: > > echo clear > /sys/kernel/debug/kmemleak > echo scan > /sys/kernel/debug/kmemleak > cat /sys/kernel/debug/kmemleak Worked fine for me. Maybe your config is special? --Andy
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