From: Uladzislau Rezki <urezki@gmail.com>
To: Herbert Xu <herbert@gondor.apana.org.au>,
"Liam R. Howlett (Google)" <liam@infradead.org>,
Michal Hocko <mhocko@suse.com>
Cc: "Liam R. Howlett (Google)" <liam@infradead.org>,
Uladzislau Rezki <urezki@gmail.com>,
Michal Hocko <mhocko@suse.com>, Baoquan He <bhe@redhat.com>,
Alexander Potapenko <glider@google.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Marco Elver <elver@google.com>, Michal Hocko <mhocko@kernel.org>,
Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Graf <tgraf@suug.ch>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
maple-tree@lists.infradead.org, Lorenzo Stoakes <ljs@kernel.org>,
Chris Mason <mason@kernel.org>, Alice Ryhl <aliceryhl@google.com>,
Andrew Ballance <andrewjballance@gmail.com>,
stable@vger.kernel.org,
"David Hildenbrand (Arm)" <david@kernel.org>
Subject: Re: [PATCH 4/4] rhashtable: fix vmalloc() deadlock in atomic rehash
Date: Fri, 30 Oct 2026 10:52:37 +0100 [thread overview]
Message-ID: <auRo5WBj2OlKlWGW@pc636> (raw)
In-Reply-To: <auQhkHG6XlgNTdRr@gondor.apana.org.au>
> On Thu, Oct 29, 2026 at 10:53:56AM -0400, Liam R. Howlett (Google) wrote:
> >
> > Given where we are in the release, this fixes a real issue that can
> > happen so maybe we take this now and settle the general handling later?
>
> There is no rush at all since the bug that you found has existed
> since 2025:
>
> commit c6307674ed82c0c57d6e1e3408e84ac449ab8e94
> Author: Uladzislau Rezki (Sony) <urezki@gmail.com>
> Date: Tue Oct 7 14:20:35 2025 +0200
>
> mm: kvmalloc: add non-blocking support for vmalloc
>
> Let's take the time to fix this properly.
>
The problem with spin_lock_irqsave() is that vmalloc() path can take
time to alloc and map pages. I am not sure this is worth to switch to
irq-save locking primitive. So this is the "heaviest" allocator in the
kernel. Callers have to be careful how the call vmalloc().
IMO, this caller has to be fixed.
--
Uladzislau Rezki
next prev parent reply other threads:[~2026-10-30 9:52 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-28 15:42 [PATCH 0/4] Lib fixes for 7.3 Liam R. Howlett (Google)
2026-10-28 15:42 ` [PATCH 1/4] maple_tree: Fix rcu reader NULL dereference after the tree is emptied Liam R. Howlett (Google)
2026-10-28 15:42 ` [PATCH 2/4] maple_tree: Test emptying tree while RCU reading Liam R. Howlett (Google)
2026-10-28 15:42 ` [PATCH 3/4] maple_tree: Update internal warning and bug_on code Liam R. Howlett (Google)
2026-10-28 17:54 ` Lorenzo Stoakes (ARM)
2026-10-28 18:37 ` Liam R. Howlett (Google)
2026-10-28 15:42 ` [PATCH 4/4] rhashtable: fix vmalloc() deadlock in atomic rehash Liam R. Howlett (Google)
2026-10-29 2:16 ` Herbert Xu
2026-10-29 10:08 ` Uladzislau Rezki
2026-10-29 14:53 ` Liam R. Howlett (Google)
2026-10-29 16:23 ` Michal Hocko
2026-10-30 4:48 ` Herbert Xu
2026-10-30 9:52 ` Uladzislau Rezki [this message]
2026-10-29 20:02 ` Matthew Wilcox
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