On Mon, Feb 01, 2021 at 10:51:03AM -0800, Joe Perches wrote:
> On Mon, 2021-02-01 at 14:15 +0000, Matthew Wilcox wrote:
> > On Mon, Feb 01, 2021 at 07:56:10PM +0800, Yafang Shao wrote:
> > > - Before the patch,
> > > [ 6343.396602] Slab 0x000000004382e02b objects=33 used=3
> > > fp=0x000000009ae06ffc flags=0x17ffffc0010200(slab|head)
> > >
> > > - After the patch,
> > > [ 6871.296131] Slab 0x00000000c0e19a37 objects=33 used=3
> > > fp=0x00000000c4902159 flags=0x17ffffc0010200(Node 0,Zone 2,Lastcpupid
> > > 0x1fffff,slab|head)
> >
> > I would suggest it will be easier to parse as:
> >
> > flags=0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff)
> >
> > That should alleviate the concerns about debugfs format change -- we've
> > never guaranteed that flag names won't change, and they now look enough
> > like flags that parsers shouldn't fall over them.
>
> Seems sensible and would make the generating code simpler too.
>
> But is it worth the vsprintf code expansion for the 5 current uses?
>
> mm/debug.c: pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags,
> &head->flags,
> mm/memory-failure.c: pr_info("soft offline: %#lx: %s
> migration failed %d, type %lx (%pGp)\n",
> mm/memory-failure.c: pr_info("soft offline: %#lx: %s isolation
> failed, page count %d, type %lx (%pGp)\n",
> mm/memory-failure.c: pr_info("%s: %#lx: unknown page type: %lx
> (%pGp)\n",
> mm/page_owner.c: "PFN %lu type %s Block %lu type %s
> Flags %#lx(%pGp)\n",
>
> Wouldn't it be more sensible just to put this code in a new function
> call in mm?
Does it matter whether the code lives in vsprintf.c or mm/debug.c? It's
built into the kernel core either way. I'm not a huge fan of the current
way %pFoo is handled, but unless/until it's drastically revised, I don't
think this proposed patch makes anything worse.
