error: the frame size of 1552 bytes is larger than 1280 bytes when building bcachefs

[Kent Overstreet]

On Thu, May 22, 2025 at 01:23:56PM +0200, Arnd Bergmann wrote:
> On Thu, May 22, 2025, at 08:39, Peng Fan wrote:
> > Hi Kent, Arnd
> >
> > There is below build error with "make ARCH=arm randconfig; make"
> >
> > fs/bcachefs/data_update.c: In function 
> > '__bch2_data_update_index_update':
> > fs/bcachefs/data_update.c:439:1: error: the frame size of 1552 bytes is 
> > larger than 1280 bytes [-Werror=frame-larger-than=]
> 
> Right, I think that's been the case with bcachefs since the start,
> and I see it with allmodconfig as well, the problem being mostly
> CONFIG_KASAN_STACK.
> 
> There are a couple of bcachefs functions that have an unusual number
> of local struct variables in them, and KASAN_STACK adds a redzone
> around each one of them, further increasing the size.
> 
> When I add "depends on !KASAN_STACK" to bcachefs, I see all
> randconfig builds succeeding, but that may not be the best
> solution.

Post 6.16, all the bcachefs functions I know of with high stack usage
run with nearly the full stack available - they're running from a
workqueue, or they're fsck, so this should be a non issue - I recently
did some testing with max stack tracing usage enabled and our stack
usage looks ok now.