Re: [regression] oops on heavy compilations ("kernel BUG at mm/zswap.c:1005!" and "Oops: invalid opcode: 0000")

[Piotr Oniszczuk]

> Wiadomość napisana przez Yosry Ahmed <yosryahmed@xxxxxxxxxx> w dniu 31.08.2024, o godz. 19:23:
> 
> On Sat, Aug 31, 2024 at 2:41 AM Piotr Oniszczuk
> <piotr.oniszczuk@xxxxxxxxx> wrote:
>> 
>> 
>> 
>>> Wiadomość napisana przez Yosry Ahmed <yosryahmed@xxxxxxxxxx> w dniu 29.08.2024, o godz. 23:54:
>>> 
>>> I also noticed that you are using z3fold as the zpool. Is the problem
>>> reproducible with zsmalloc? I wouldn't be surprised if there's a
>>> z3fold bug somewhere.
>>> 
>> 
>> Hmm - yesterday i recompiled 6.9.12 with zsmalloc and …. after 16h of continuous tests I can’t reproduce issue.
>> With zsmalloc 6.9.12 looks to me like stable.
> 
> Interesting, and a little bit what I hoped for tbh.

:-)

I tested mainline 6.10.7 with 26h test and also it is stable with zsmalloc 

> 
>> 
>> With this - what will be your advice to move forward?
> 
> Well, it's possible that some zswap change was not fully compatible
> with z3fold, or surfaced a dormant bug in z3fold. Either way, my
> recommendation is to use zsmalloc.
> I have been trying to deprecate

IMHO - isn’t bug in this report + difficulties to reproduce->fix enough to depreciate z3fold?  

> z3fold, and honestly you are the only person I have seen use z3fold in
> a while -- which is probably why no one else reported such a problem.

Well - in fact this is ArchLinux - not me.
I’m using Arch and kernel in builder machine with ArchLinux config + packaging

> 
>> Is there any possibility/way to avoid bisecting? (due limited time from my side)
> 
> So unless you have a reason to specifically use z3fold or avoid
> zsmalloc, please use zsmalloc. It should be better for you anyway. I

I see benefits already: on very memory demanding qtwebkit compile:
z3fold: swap frequently gets 6..8G from 16G available
zsmalloc: can’t see more than 1..2G
  
> doubt that you (or anyone) wants to spend time debugging a z3fold
> problem :)

lets depreciate it!