Re: [PATCH hotfix 6.12] maple_tree: correct tree corruption on spanning store

[Bert Karwatzki]

Am Samstag, dem 05.10.2024 um 12:17 +0100 schrieb Lorenzo Stoakes:
> On Sat, Oct 05, 2024 at 07:41:14AM +0100, Lorenzo Stoakes wrote:
> > Writing a data range into a maple tree may involve overwriting a number of
> > existing entries that span across more than one node. Doing so invokes a
> > 'spanning' store.
> >
>
> [snip]
>
> Andrew - just to note that I have intentionally left stable off this, in
> order that wre can allow this to stabilise in the 6.12 release candidates.
>
> Up until 6.12 this bug seemed much harder to hit, and as far as I'm aware
> we've never had a bug report for it prior to this.

I still suspect that this could have been the same error:
https://lkml.org/lkml/2024/8/28/1558
When compiling the kernel without CONFIG_DEBUG_VM maple tree bug results in an
unkillable task, and when trying to kill it first produced the rwsem warning
(and soon after took down the whole system).
But I couldn't reproduce it with the given reproducer, either.

Bert Karwatzki