Re: [PATCH 0/2] Fix memory corruption with FSMonitor-enabled unpack_trees()

Hi Stolee,

On Wed, 17 Mar 2021, Derrick Stolee wrote:

On 3/17/2021 11:30 AM, Johannes Schindelin via GitGitGadget wrote:

quoted

While dog-fooding Jeff Hostetler's FSMonitor patches, I ran into a really
obscure segmentation fault during one of my epic Git for Windows rebases.

Thanks for dogfooding!

I'm completely selfish here, as I want to benefit from the speed myself,
and that's also the reason why I added this as an experimental option to
Git for Windows v2.31.0: That way, I can test it everywhere (and so can
others).

quoted

Turns out that this bug is quite old.

A little over a year, yes, since the v2 hook was committed. It's old
enough that these could be applied to 'maint'.

Indeed. Even better: if you look closely at the GitGitGadget PR, you will
see that I based it on `kw/fsmonitor-watchman-racefix`.

quoted

Johannes Schindelin (2):
  fsmonitor: fix memory corruption in some corner cases
  fsmonitor: do not forget to release the token in `discard_index()`

The patches themselves are correct and describe the problem well.
They only show up during non-trivial uses of FS Monitor and index
updates, so I understand your hesitance to write tests that trigger
these problems.

Right. For me, I ran into them only in one specific instance, when
rebasing Git for Windows' patch thicket onto `seen`, and then only when
merging a topic branch with a rather big diff.

Thanks,
Dscho