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* /proc/*/maps broken on nommu
@ 2023-09-17 11:38 Max Filippov
  2023-09-17 15:06 ` Randy Dunlap
  0 siblings, 1 reply; 2+ messages in thread
From: Max Filippov @ 2023-09-17 11:38 UTC (permalink / raw)
  To: LKML, Linux Memory Management List
  Cc: Matthew Wilcox, Yu Zhao, Liam R. Howlett, Vlastimil Babka,
	Davidlohr Bueso, Andrew Morton

Hello,

As of v6.5 cat /proc/*/maps produces empty output on nommu xtensa systems.
Bisection points to the commit 0c563f148043 ("proc: remove VMA rbtree
use from nommu").
It looks like the issue may be not in the m_start (where find_vma(mm,
addr) returns
NULL), but in the nommu version of find_vma itself. I've tried replacing nommu
find_vma implementation with an implementation of the MMU version and it
fixes the /proc/*/maps output. Kind of (it works as expected on one of
my systems,
but consistently locks up on the other).

Any suggestions of what might be wrong/how to fix it properly?

-- 
Thanks.
-- Max


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: /proc/*/maps broken on nommu
  2023-09-17 11:38 /proc/*/maps broken on nommu Max Filippov
@ 2023-09-17 15:06 ` Randy Dunlap
  0 siblings, 0 replies; 2+ messages in thread
From: Randy Dunlap @ 2023-09-17 15:06 UTC (permalink / raw)
  To: Max Filippov, LKML, Linux Memory Management List
  Cc: Matthew Wilcox, Yu Zhao, Liam R. Howlett, Vlastimil Babka,
	Davidlohr Bueso, Andrew Morton



On 9/17/23 04:38, Max Filippov wrote:
> Hello,
> 
> As of v6.5 cat /proc/*/maps produces empty output on nommu xtensa systems.
> Bisection points to the commit 0c563f148043 ("proc: remove VMA rbtree
> use from nommu").
> It looks like the issue may be not in the m_start (where find_vma(mm,
> addr) returns
> NULL), but in the nommu version of find_vma itself. I've tried replacing nommu
> find_vma implementation with an implementation of the MMU version and it
> fixes the /proc/*/maps output. Kind of (it works as expected on one of
> my systems,
> but consistently locks up on the other).
> 
> Any suggestions of what might be wrong/how to fix it properly?
> 

Hi Max,

There is already a proposed patch and some discussion:

https://lore.kernel.org/lkml/20230915160055.971059-2-ben.wolsieffer@hefring.com/

-- 
~Randy


^ permalink raw reply	[flat|nested] 2+ messages in thread

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