linux-kernel - Re: [GIT PULL] bcachefs

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Date:   Mon, 26 Jun 2023 23:22:07 -0400
From:   Kent Overstreet <kent.overstreet@...ux.dev>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Jens Axboe <axboe@...nel.dk>, torvalds@...ux-foundation.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-bcachefs@...r.kernel.org, Christoph Hellwig <hch@....de>
Subject: Re: [GIT PULL] bcachefs

On Tue, Jun 27, 2023 at 04:19:33AM +0100, Matthew Wilcox wrote:
> On Mon, Jun 26, 2023 at 08:59:44PM -0600, Jens Axboe wrote:
> > On 6/26/23 8:33?PM, Kent Overstreet wrote:
> > > On Mon, Jun 26, 2023 at 07:13:54PM -0600, Jens Axboe wrote:
> > >> fs/bcachefs/alloc_background.c: In function ?bch2_check_alloc_info?:
> > >> fs/bcachefs/alloc_background.c:1526:1: warning: the frame size of 2640 bytes is larger than 2048 bytes [-Wframe-larger-than=]
> > >>  1526 | }
> > >>       | ^
> > >> fs/bcachefs/reflink.c: In function ?bch2_remap_range?:
> > >> fs/bcachefs/reflink.c:388:1: warning: the frame size of 2352 bytes is larger than 2048 bytes [-Wframe-larger-than=]
> > >>   388 | }
> > >>       | ^
> > > 
> > > What version of gcc are you using? I'm not seeing either of those
> > > warnings - I'm wondering if gcc recently got better about stack usage
> > > when inlining.
> > 
> > Using:
> > 
> > gcc (Debian 13.1.0-6) 13.1.0
> > 
> > and it's on arm64, fwiw.
> 
> OOI what PAGE_SIZE do you have configured?  Sometimes fs data structures
> are PAGE_SIZE dependent (haven't looked at this particular bcachefs data
> structure).  We've also had weirdness with various gcc versions on some
> architectures making different inlining decisions from x86.

There are very few references to PAGE_SIZE in bcachefs, I've killed off
as much of that as I can because all this code has to work in userspace
too and depending on PAGE_SIZE is sketchy there