Re: [PATCH] x86/dumpstack/64: Don't evaluate exception stacks before setup

2019-10-23 Thread Josh Poimboeuf
On Wed, Oct 23, 2019 at 08:05:49PM +0200, Thomas Gleixner wrote: > Cyrill reported the following crash: > > BUG: unable to handle page fault for address: 1ff0 > #PF: supervisor read access in kernel mode > RIP: 0010:get_stack_info+0xb3/0x148 > > It turns out that if the stack

Re: [PATCH] x86/dumpstack/64: Don't evaluate exception stacks before setup

2019-10-23 Thread Cyrill Gorcunov
On Wed, Oct 23, 2019 at 11:31:40AM -0700, Matthew Wilcox wrote: > On Wed, Oct 23, 2019 at 08:05:49PM +0200, Thomas Gleixner wrote: > > Prevent this by checking the validity of the cea_exception_stack base > > address and bailing out if it is zero. > > Could also initialise cea_exception_stack to

Re: [PATCH] x86/dumpstack/64: Don't evaluate exception stacks before setup

2019-10-23 Thread Matthew Wilcox
On Wed, Oct 23, 2019 at 08:05:49PM +0200, Thomas Gleixner wrote: > Prevent this by checking the validity of the cea_exception_stack base > address and bailing out if it is zero. Could also initialise cea_exception_stack to -1? That would lead to it being caught by ... > end = begin +

[PATCH] x86/dumpstack/64: Don't evaluate exception stacks before setup

2019-10-23 Thread Thomas Gleixner
Cyrill reported the following crash: BUG: unable to handle page fault for address: 1ff0 #PF: supervisor read access in kernel mode RIP: 0010:get_stack_info+0xb3/0x148 It turns out that if the stack tracer is invoked before the exception stack mappings are initialized