linux-kernel - Re: [RFC][PATCH 00/17] Fix up the recent SRSO patches

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Date: Tue, 16 Apr 2024 06:48:54 +0000
From: a-development@...teo.de
To: Borislav Petkov <bp@...en8.de>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, peterz@...radead.org,
 David.Kaplan@....com, Andrew.Cooper3@...rix.com, jpoimboe@...nel.org,
 gregkh@...uxfoundation.org
Subject: Re: [RFC][PATCH 00/17] Fix up the recent SRSO patches

It worked, it worked!

https://up.tail.ws/txt/working-suspend.txt

I've tested it now quite some time.
But, I also had to start using 6.6.26-1-lts because my magewell capture 
card wouldn't without.

Thanks again!

On 26.03.2024 23:21, Borislav Petkov wrote:
> Whoops,
> 
> this fell through the cracks. Sorry about that.
> 
> On Mon, Jan 29, 2024 at 06:18:00PM +0000, a-development@...teo.de 
> wrote:
>> I have the feeling that something else is amiss.
>> Currently under 6.7.2-2-cachyos with srso=off.
>> https://0x0.st/HDqP.txt
> 
> Yah, your tasks refuse to freeze on suspend and they have this fuse
> stuff in the stacktrace:
> 
> [ 6346.492593] task:btop            state:D stack:0     pid:279617
> tgid:1548  ppid:1531   flags:0x00004006
> [ 6346.492600] Call Trace:
> [ 6346.492602]  <TASK>
> [ 6346.492607]  __schedule+0xd44/0x1af0
> [ 6346.492614]  ? srso_alias_return_thunk+0x5/0xfbef5
> [ 6346.492617]  ? __wake_up+0x9d/0xc0
> [ 6346.492622]  schedule+0x32/0xd0
> [ 6346.492627]  request_wait_answer+0xd0/0x2a0 [fuse
> db37c699d94393e946cf93306449ea0f307959a1]
> [ 6346.492638]  ? __pfx_autoremove_wake_function+0x10/0x10
> [ 6346.492643]  fuse_simple_request+0x21c/0x390 [fuse
> db37c699d94393e946cf93306449ea0f307959a1]
> [ 6346.492653]  fuse_statfs+0xf2/0x160 [fuse
> db37c699d94393e946cf93306449ea0f307959a1]
> [ 6346.492667]  statfs_by_dentry+0x67/0x90
> 
>> 
>> Now I feel, further communication is rather selfish, as a clean 
>> environment
>> is hard to provide.
>> In any case, my FUSE arguments are sshfs -o kernel_cache -o auto_cache 
>> -o
>> reconnect \
>>                -o compression=yes -o cache_timeout=600 -o
>> ServerAliveInterval=30 \
>>                "$source" "$target" -o idmap=user
>> 
>> With this line, I somehow managed to have the FUSE mount infinitely 
>> mounted,
>> even if the device was offline for couple of days.
>> A followed suspend would fail to freeze.
>> srso=off would reproducibly work.
> 
> Not in your example above. It would fail after a couple of suspend
> cycles.
> 
> And looking at your splats
> 
> [ 6366.524953]  ? switch_fpu_return+0x50/0xe0
> [ 6366.524956]  ? srso_alias_return_thunk+0x5/0xfbef5
> 		  ^^^^^^^^^^^^^^^^^^^^^^^^
> [ 6366.524958]  ? exit_to_user_mode_prepare+0x132/0x1f
> 
> the right cmdline option to disable it is:
> 
> spec_rstack_overflow=off
> 
> not
> 
> srso=off
> 
> :-)
> 
>> Please provide me a specific version of a kernel I should try in my
>> configuration to try and reproduce.
>> I'd prefer a pre-compiled one; if not tell me...
>> I use archlinux.
> 
> Just build the latest released kernel, which is 6.8 now. Take your
> .config and use it to build it. The net is full of tutorials how to do
> so.
> 
> And then try with spec_rstack_overflow=off and let's see what that 
> does.
> 
>> Please give me a reason to not feel bad about myself.
> 
> Don't worry - it's just a machine. :)