Re: Linux6.14-rc5 BUG: spinlock bad magic in z3fold_zpool_free

[Nhat Pham]

On Wed, Mar 26, 2025 at 10:32 AM Nhat Pham <nphamcs@xxxxxxxxx> wrote:
>
> On Wed, Mar 26, 2025 at 10:11 AM ffhgfv <xnxc22xnxc22@xxxxxx> wrote:
> >
> > Hello, I found a bug titled " BUG: spinlock bad magic in z3fold_zpool_free   " with modified syzkaller in the Linux6.14-rc5.
> > If you fix this issue, please add the following tag to the commit:  Reported-by: Jianzhou Zhao <xnxc22xnxc22@xxxxxx>,    xingwei lee <xrivendell7@xxxxxxxxx>, Zhizhuo Tang <strforexctzzchange@xxxxxxxxxxx>
>
> Please stop using z3fold :) We already removed it upstream.

To clarify a little bit - we've found that z3fold is buggy (for a very
long time), and does not outperform zsmalloc in many of the workloads
we test on (both microbenchmark and real production workloads). We've
deprecated it since 6.12:

https://github.com/torvalds/linux/commit/7a2369b74abf76cd3e54c45b30f6addb497f831b

and will remove it altogether:

https://lore.kernel.org/all/20250129180633.3501650-1-yosry.ahmed@xxxxxxxxx/

Perhaps Vitaly can fix the issue for stability's sake (or in case
there is a reason why you MUST use z3fold)? But I strongly recommend
you experiment with zsmalloc :)