From: Dominique Martinet <asmadeus@codewreck.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: syzbot <syzbot+de6fd6789748a8aa64a0@syzkaller.appspotmail.com>,
apopple@nvidia.com, byungchul@sk.com, david@kernel.org,
gourry@gourry.net, joshua.hahnjy@gmail.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
matthew.brost@intel.com, rakie.kim@sk.com,
syzkaller-bugs@googlegroups.com, ying.huang@linux.alibaba.com,
ziy@nvidia.com, Eric Van Hensbergen <ericvh@kernel.org>,
Latchesar Ionkov <lucho@ionkov.net>,
Christian Schoenebeck <linux_oss@crudebyte.com>,
v9fs@lists.linux.dev,
Nguyen Ngoc Thang <ngocthang2710.1999@gmail.com>
Subject: Re: [syzbot] [mm?] WARNING in v9fs_fid_get_acl (2)
Date: Tue, 22 Sep 2026 17:45:14 +0900 [thread overview]
Message-ID: <arJAGlhkDJbcy2sw@codewreck.org> (raw)
In-Reply-To: <20260919031451.3f47a8da8405e88fa1ab5398@linux-foundation.org>
(+Nguyen in Cc as he tried resending sloppy patches after this)
Andrew Morton wrote on Sat, Sep 19, 2026 at 03:14:51AM -0700:
> > WARNING: mm/page_alloc.c:5340 at alloc_order_allowed mm/page_alloc.c:5340 [inline], CPU#0: syz.1.357/7872
> > WARNING: mm/page_alloc.c:5340 at __alloc_frozen_pages_noprof+0x2137/0x3300 mm/page_alloc.c:5397, CPU#0: syz.1.357/7872
>
> Thanks. Caused by an old v9fs bug. A fix was proposed but never merged:
> https://lists.openwall.net/linux-kernel/2024/02/02/806?utm_source=chatgpt.com
Right, we've been going in circle with this since forever, and nobody
answered Christian Schoenebeck's question[1] about what the limit should
be, and while I don't care much ultimately I sort of agree with him
(e.g. limit should be XATTR_SIZE_MAX for anything that the VFS layer
touches, but acl are converted within the 9p subsystem and could be
arbitrarily large so status quo of a KMALLOC_MAX_SIZE limit because they
could come from something else)
Andrew, if you have an opinion on whether we should cap the acl sizes
anyway, please say...
[1] https://lore.kernel.org/all/Z1n-Ue19Pa_AWVu0@codewreck.org/T/#md7c1e009696501b3b87940cb613150bdebd1db28
--
Dominique Martinet | Asmadeus
next prev parent reply other threads:[~2026-09-22 8:45 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-19 5:07 [syzbot] [mm?] WARNING in v9fs_fid_get_acl (2) syzbot
2026-09-19 10:14 ` Andrew Morton
2026-09-22 8:45 ` Dominique Martinet [this message]
2026-09-23 2:08 ` Andrew Morton
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