Re: [PATCH] Revert "exec: make de_thread() freezable (was: Re: Linux 4.20-rc4)
From: Ingo Molnar
Date: Tue Dec 04 2018 - 04:33:16 EST
* Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> I dunno. I do not use hibernation. I am a heavy user of the suspend
> though. I s2ram all the time. And I have certainly experienced cases
> where suspend has failed and I onlyi found out later when I've picked
> up my laptop from my heat up bag. Nothing fatal has resulted from that
> but this is certainly annoying.
Hm, so I (mistakenly) thought freezing was mostly limited to hibernation
and to a few weird cases when in flight DMA must not be suspended - but
I'm wrong and in practice we always freeze tasks during s2ram, right?
And indeed:
config SUSPEND_FREEZER
bool "Enable freezer for suspend to RAM/standby" \
if ARCH_WANTS_FREEZER_CONTROL || BROKEN
depends on SUSPEND
default y
which is essentially always enabled on x86.
TIL ...
s2ram is obviously a huge deal.
Just a newbie question: any chance to not do any freezing at all on
modern laptops when doing s2ram, or at least only warn if it fails and
try to suspend?
Because in practice losing power due to failed freezing *will* result in
data loss, in about 90% of the time ...
So I don't even know what we are trying to protect against by refusing to
freeze - avoiding a 0.001% data loss risk against a 90% data loss risk?
Thanks,
Ingo