Messages in this thread | | | Date | Tue, 6 Feb 2018 21:16:17 -0500 | From | Theodore Ts'o <> | Subject | Re: [PATCHv2 1/1] ext4: don't put symlink in pagecache into highmem |
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On Tue, Feb 06, 2018 at 03:38:09PM -0800, Eric Biggers wrote: > I don't think backporting this change for other filesystems is particularly > important, since if I understand correctly, the reasons that Al made the change > originally were: > > - to allow following symlinks in RCU mode, but that's not implemented in old > kernels
Yup.
> - to prevent a process from using up all kmaps and deadlocking the system, which > I'm not sure is a real problem (someone would need to try to put together a > reproducer), but if so it would probably just be a local device of service.
.. and *that's* only a problem on 32-bit systems. And aside from Android, it's unclear to me how much we need to support 32-bit systems on upstream LTS kernels. I suppose there might be Rasperry PI's which are 32-bits and which might want to use btrfs. Personally I'm not sure we should care all that much, but others who care more about LTS kernels and 32-bit systems might have a different opinion.
> Also if we actually backported the full commit there are follow-on fixes such as > e8ecde25f5e that would be needed as well but might be missed.
Good point.
- Ted
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