Re: [syzbot ci] Re: make vmalloc gfp flags usage more apparent

Uladzislau Rezki
2025-11-13T16:54:20Z

On Thu, Nov 13, 2025 at 08:48:41AM -0800, Vishal Moola (Oracle) wrote:
> On Thu, Nov 13, 2025 at 02:33:31PM +0100, Uladzislau Rezki wrote:
> > On Wed, Nov 12, 2025 at 11:41:37PM -0800, syzbot ci wrote:
> > > syzbot ci has tested the following series
> > >
> > > [v2] make vmalloc gfp flags usage more apparent
> > > https://lore.kernel.org/all/20251112185834.32487-1-vishal.moola@gmail.com
> > > * [PATCH v2 1/4] mm/vmalloc: warn on invalid vmalloc gfp flags
> > > * [PATCH v2 2/4] mm/vmalloc: Add a helper to optimize vmalloc allocation gfps
> > > * [PATCH v2 3/4] mm/vmalloc: cleanup large_gfp in vm_area_alloc_pages()
> > > * [PATCH v2 4/4] mm/vmalloc: cleanup gfp flag use in new_vmap_block()
> > >
> > > and found the following issue:
> > > WARNING: kmalloc bug in bpf_prog_alloc_no_stats
> > >
> > > Full report is available here:
> > > https://ci.syzbot.org/series/46d6cb1a-188d-4ff5-8fab-9c58465d74d3
> > >
> > > ***
> > >
> > > WARNING: kmalloc bug in bpf_prog_alloc_no_stats
> > >
> > > tree: linux-next
> > > URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next
> > > base: b179ce312bafcb8c68dc718e015aee79b7939ff0
> > > arch: amd64
> > > compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> > > config: https://ci.syzbot.org/builds/3449e2a5-35e0-4eac-86c6-97ca0ec741d7/config
> > >
> > > ------------[ cut here ]------------
> > > Unexpected gfp: 0x400000 (__GFP_ACCOUNT). Fixing up to gfp: 0xdc0 (GFP_KERNEL|__GFP_ZERO). Fix your code!
> > > WARNING: mm/vmalloc.c:3938 at vmalloc_fix_flags+0x9c/0xe0, CPU#1: syz-executor/6079
> > > Modules linked in:
> > >
> > Again bpf :)
> >
> > GFP_KERNEL_ACCOUNT? I saw there have been __GFP_HARDWALL added already,
> > IMO it is worth to replace it by "high level flag", which is GFP_USER.
>
> Yeah I'll replace __GFP_HARDWALL with GFP_USER, and add
> GFP_KERNEL_ACCOUNT. At this point I'll just add GFP_NOFS and GFP_NOIO
> as well so its easier to understand the mask.
>
Sounds good!

--
Uladzislau Rezki