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Fri, 30 Oct 2026 02:52:40 -0700 (PDT) Received: from pc636 ([2001:9b1:d5a0:a500::800]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6b4d7b1d556sm432290a12.28.2026.10.30.02.52.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Oct 2026 02:52:40 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Fri, 30 Oct 2026 10:52:37 +0100 To: Herbert Xu , "Liam R. Howlett (Google)" , Michal Hocko Cc: "Liam R. Howlett (Google)" , Uladzislau Rezki , Michal Hocko , Baoquan He , Alexander Potapenko , Andrey Ryabinin , Marco Elver , Michal Hocko , Linux Crypto Mailing List , Andrew Morton , Thomas Graf , linux-mm@kvack.org, linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org, Lorenzo Stoakes , Chris Mason , Alice Ryhl , Andrew Ballance , stable@vger.kernel.org, "David Hildenbrand (Arm)" Subject: Re: [PATCH 4/4] rhashtable: fix vmalloc() deadlock in atomic rehash Message-ID: References: <20261028154218.1668182-1-liam@infradead.org> <20261028154218.1668182-5-liam@infradead.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: > 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) > 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