From: Andi Kleen <ak@suse.de>
To: Badari Pulavarty <pbadari@gmail.com>
Subject: Re: Was: boot failure, "DWARF2 unwinder stuck at 0xc0100199"
Date: Thu, 31 Aug 2006 20:32:34 +0200
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References: <20060820013121.GA18401@fieldses.org> <200608312010.20874.ak@suse.de> <1157049193.22667.19.camel@dyn9047017100.beaverton.ibm.com>
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On Thursday 31 August 2006 20:33, Badari Pulavarty wrote:
> On Thu, 2006-08-31 at 20:10 +0200, Andi Kleen wrote:
> 
> > Should be fixed in .19
> 
> Andi,
> 
> I am looking at the "validity" of the stack traces. What I 
> find is that "unwinder" is skipping few stack frames..
> 
> As you can see from the following stack - it shows 
> 
> 	msync_interval() -> 
> 		set_page_dirty() -> 
> 			__set_page_dirty_buffers()
> 
> But actual trace is (looking at the code):
> 
> 	msync_interval() -> 
> 	 	msync_page_range() ->
> 		   msync_pud_range() -> 
> 		      msync_pgd_range() ->
> 			 msync_pte_range() ->	
> 				set_page_dirty() -> 
> 					__set_page_dirty_buffers()
> 
> Why is it skipping all msync_page/pud/pgd/pte_range() routines ?

Most likely because they're inlined. gcc tends to always inline static functions
with only a single caller, which is usually true for all the nested page table functions 
in mm/*.  Inlined functions (or tail called functions like return foo()) are invisible 
to the unwinder.

-Andi


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