Re: [PATCH v1 1/2] mm: rename AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM to AS_WRITEBACK_MAY_HANG

["David Hildenbrand (Red Hat)" <david@kernel.org>]

On 11/20/25 19:42, Joanne Koong wrote:
> AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM was added to avoid waiting on
> writeback during reclaim for inodes belonging to filesystems where
> a) waiting on writeback in reclaim may lead to a deadlock or
> b) a writeback request may never complete due to the nature of the
> filesystem (unrelated to reclaim)
> 
> Rename AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM to the more generic
> AS_WRITEBACK_MAY_HANG to reflect mappings where writeback may hang where
> the cause could be unrelated to reclaim.
> 
> This allows us to later use AS_WRITEBACK_MAY_HANG to mitigate other
> scenarios such as possible hangs when sync waits on writeback.

Hmm, there is a difference whether writeback may hang or whether 
writeback may deadlock.

In particular, isn't it the case that writeback on any filesystem might 
effectively hang forever on I/O errors etc?

Is this going back to the previous flag semantics before we decided on 
AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM? (I'd have to look at the previous 
discussions, but "writeback may take an indefinite amount" in patch #2 
pretty much looks like what I remember there)

-- 
Cheers

David