Re: [PATCH] fsck: do not loop infinitely when processing packs

From: Patrick Steinhardt <ps@pks.im>
Date: Feb 23, 2026, 09:36 UTC
Message-ID: <aZwfmXG113t6OsUH@pks.im>
In-Reply-To: <20260223092523.GA209277@coredump.intra.peff.net>

On Mon, Feb 23, 2026 at 04:25:23AM -0500, Jeff King wrote:

Show 14 quoted lines

> On Mon, Feb 23, 2026 at 09:46:00AM +0100, Patrick Steinhardt wrote:
> 
> > As pointed out in [1] the root cause is actually something different,
> > and we merely expose this now with the MRU-based iteration. But I
> > wouldn't mind if we eventually switched back to maintaining two lists,
> > or finding a different way for how to maintain the iteration order.
> 
> Maybe I don't understand what you're saying, but isn't the root cause
> the same?
> 
> Code is iterating the list, and then during that iteration calls
> find_pack_entry(). The fact that fsck only calls find_pack_entry() in
> some subset of cases is immaterial, I'd think. The risk is always there
> when iterating now.

It is, true. All I'm saying is that the problem runs a bit deeper, and that fixing the actual root cause would also fix the issue reported by brian.

So we might want to have another look at hardening packfile iteration either by reinstating the second list for iteration or by extending `repo_for_each_pack()` to also set the `skip_updating_mru` bit. Over time though I'd rather get rid of `repo_for_each_pack()`, and once that is the case and packed object iteration is neatly encapsulated in the backend the risk of only having the MRU will be significantly reduced.

Thanks!

Patrick