Re: [Crash-utility] The problems when running SuSE 12 on VirtualBox

----- Original Message ----- > On 11/19/2015 08:37 AM, David Mair wrote: >> On 11/19/2015 07:45 AM, Dave Anderson wrote: >> >> Hi Dave, >> >>> ----- Original Message ----- >> <snip> >>> >>>> (2) Execute "crash -d8" on physical machine will cause crash utility core >>>> dump. >>> >>> I can reproduce this, so I'll look into it. It's related to the /dev/mem "test" >>> to determine whether the kernel was configured with CONFIG_STRICT_DEVMEM, where >>> it tries to read from pfn 257 (just above the CONFIG_STRICT_DEVMEM limit), but >>> gets into an infinite loop when used in conjunction with -d. >>> >>> Anyway, just continue to use /proc/kcore and you should be fine. >> >> This is the cause in readmem(): >> >> switch(READMEM(...)) >> { >> . >> . >> . >> case READ_ERROR: >> if (PRINT_ERROR_MESSAGE) ********** THIS *********** >> { >> causes a nested readmem() call before the goto gives it >> to the caller to deal with >> } >> goto readmem_error >> } >> . >> . >> . >> switch(error_handle) >> { >> case (RETURN_ON_ERROR): >> } >> >> The PRINT_ERROR_MESSAGE I assume is an escalation from -d 8 in this case. >> > > The whole switch_to_proc_kcore() probably shouldn't be conditional on > the presence of PRINT_ERROR_MESSAGE, only the actual error message > should be. > > Patch shortly. > > -- > David. Yeah, I agree. It was done that way to catch the very first non-QUIET readmem() call from kernel_init(), and make the bait-and-switch right there. Without the CRASHDEBUG(x) override, it works as-is because the readmem() calls in devmem_is_restricted() are purposely set to QUIET. So we're thinking something like this, right?: diff --git a/memory.c b/memory.c index 824b3ae..2282ba9 100644 --- a/memory.c +++ b/memory.c @@ -2207,13 +2207,12 @@ readmem(ulonglong addr, int memtype, void *buffer, long size, goto readmem_error; case READ_ERROR: - if (PRINT_ERROR_MESSAGE) { - if ((pc->flags & DEVMEM) && (kt->flags & PRE_KERNEL_INIT) && - devmem_is_restricted() && switch_to_proc_kcore()) - return(readmem(addr, memtype, bufptr, size, - type, error_handle)); + if ((pc->flags & DEVMEM) && (kt->flags & PRE_KERNEL_INIT) && + !(error_handle & QUIET) && devmem_is_restricted() && switch_to_proc_kcore()) + return(readmem(addr, memtype, bufptr, size, + type, error_handle)); + if (PRINT_ERROR_MESSAGE) error(INFO, READ_ERRMSG, memtype_string(memtype, 0), addr, type); - } goto readmem_error; case PAGE_EXCLUDED: Works for me, and is better than hiding a recursive-call check in devmem_is_restricted().