Re: [PATCH 2/2] ARC: show_regs: fix lockdep splat for good

2018-12-24 Thread Michal Hocko
On Fri 21-12-18 09:55:34, Vineet Gupta wrote: > On 12/21/18 5:04 AM, Michal Hocko wrote: [...] > > Yes, the fix might be more involved but I would much rather prefer a > > correct code which builds on solid assumptions. > > Right so the first step is reverting the disabled semantics for ARC and do

Re: [PATCH 2/2] ARC: show_regs: fix lockdep splat for good

2018-12-21 Thread Vineet Gupta
On 12/21/18 5:04 AM, Michal Hocko wrote: >> I presume you are referring to original commit, not my anti-change in ARC >> code, >> which is actually re-enabling it. > > Yes, but you are building on a broken concept I believe. Not sure where this is heading. Broken concept was introduced by disabl

Re: [PATCH 2/2] ARC: show_regs: fix lockdep splat for good

2018-12-21 Thread Michal Hocko
On Fri 21-12-18 14:04:04, Michal Hocko wrote: [...] > Yes, but you are building on a broken concept I believe. What > implications does re-enabling really have? Now you could reschedule and > you can move to another CPU. Is this really safe? I believe that yes > because the preemption disabling is

Re: [PATCH 2/2] ARC: show_regs: fix lockdep splat for good

2018-12-21 Thread Michal Hocko
On Thu 20-12-18 18:45:48, Vineet Gupta wrote: > On 12/20/18 5:04 AM, Michal Hocko wrote: > > On Tue 18-12-18 10:53:59, Vineet Gupta wrote: > >> signal handling core calls ARCH show_regs() with preemption disabled > >> which causes __might_sleep functions such as mmput leading to lockdep > >> splat.

Re: [PATCH 2/2] ARC: show_regs: fix lockdep splat for good

2018-12-20 Thread Vineet Gupta
On 12/20/18 5:04 AM, Michal Hocko wrote: > On Tue 18-12-18 10:53:59, Vineet Gupta wrote: >> signal handling core calls ARCH show_regs() with preemption disabled >> which causes __might_sleep functions such as mmput leading to lockdep >> splat. Workaround by re-enabling preemption temporarily. >> >

Re: [PATCH 2/2] ARC: show_regs: fix lockdep splat for good

2018-12-20 Thread Michal Hocko
On Tue 18-12-18 10:53:59, Vineet Gupta wrote: > signal handling core calls ARCH show_regs() with preemption disabled > which causes __might_sleep functions such as mmput leading to lockdep > splat. Workaround by re-enabling preemption temporarily. > > This may not be as bad as it sounds since the

[PATCH 2/2] ARC: show_regs: fix lockdep splat for good

2018-12-18 Thread Vineet Gupta
signal handling core calls ARCH show_regs() with preemption disabled which causes __might_sleep functions such as mmput leading to lockdep splat. Workaround by re-enabling preemption temporarily. This may not be as bad as it sounds since the preemption disabling itself was introduced for a supres