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Mon, 26 Oct 2026 10:40:00 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Mon, 26 Oct 2026 18:39:58 +0100 To: Andrew Morton Cc: "Uladzislau Rezki (Sony)" , linux-mm@kvack.org, Baoquan He , LKML , "David Hildenbrand (Arm)" Subject: Re: [PATCH] mm/vmalloc: Bail out if in softirq context Message-ID: References: <20261026102503.30860-1-urezki@gmail.com> <20261026090421.e4bd83f3e20fb82852abec4e@linux-foundation.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261026090421.e4bd83f3e20fb82852abec4e@linux-foundation.org> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 1DE5FC0008 X-Stat-Signature: ypx364g6imne3iwgow45zm1e3d5frpwn X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793036402-294745 X-HE-Meta: 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 xMpTDyoL f5r6J5RZeEj6ZJ/yy1nkqNMkiHh8GjWRcKVhX4NEiqEiv5PHb2Pczu8B53w+p5CDWl2ufh/7nBrqSAp5+iIOOr0RaFS3bIaQnaj5p9gd81XHDc+u3ViOQ5yQKfexwRmhjpeCZAeG9hhVIWf/A5eJW4R+58SJ2iii9z+6J26l7uwp7y+HaH7PN+rdz3vWoQYNRWxdLaonbQlu+B/Ub/K6DhhKvRLyO4FeMOUZ91x3m56JmDtK/ZU7Ll/uuiFftDqubHESCtDKa8Jq7kB72nWE5tDFFpkYHSUgO7r3SuAUlaqSItNcrWz3TPqs7IYWfD/npSBwCCtPtTsujYf8yE1qrVIZEBKtwpKSpNYXrWMCx3HlSAjJgt2GZOhZ6CIRABKptj/IyMZLx7NQPDCIL8uBunI+M/zli3cZE8Mu46HyFdunp9TMiwnpkyC3N3IHlRlb2dHPWjriQ2mrHQhWqMkSFA8rtjA4zBNUi3ymVyLriEHlj9kk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Mon, Oct 26, 2026 at 09:04:21AM -0700, Andrew Morton wrote: > On Mon, 26 Oct 2026 11:25:03 +0100 "Uladzislau Rezki (Sony)" wrote: > > > vmalloc() is not allowed to be invoked from the NMI, > > hard-irq and softirq contexts because doing so may > > deadlock on internal locks. > > > > Commit 04aa71da5f35 ("mm/vmalloc: do not trigger BUG() > > on BH disabled context") replaced the deprecated in_interrupt() > > macro with explicit in_nmi() and in_hardirq() checks, but > > unintentionally dropped the softirq context check. > > > > Example: > > > > > > vzalloc() in a task > > spin_lock(&vn->busy.lock) > > <------ Hard irq > > irq_exit() > > process softirq on the same CPU > > vmalloc() > > spin_lock(&vn->busy.lock) > > spins forever > > > > > > Restore the check by checking the caller's context with > > the in_serving_softirq() helper. Note that, it is still > > allowed to invoke vmalloc() with disabled bottom halves. > > > > Replace BUG_ON() with WARN_ON_ONCE() for in_nmi() and > > in_hardirq() case. > > > > Cc: David Hildenbrand (Arm) > > Fixes: 04aa71da5f35 ("mm/vmalloc: do not trigger BUG() on BH disabled context") > > Sounds like a cc:stable is needed? > Yes. Should i resend and put cc:stable? > > Signed-off-by: Uladzislau Rezki (Sony) > > --- > > mm/vmalloc.c | 8 +++++++- > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index 7521b9b3bfd2..36e6e3be6ba4 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -3252,7 +3252,13 @@ struct vm_struct *__get_vm_area_node(unsigned long size, > > struct vm_struct *area; > > unsigned long requested_size = size; > > > > - BUG_ON(in_nmi() || in_hardirq()); > > + /* IRQ re-entrancy -> irq_exit() -> process softirq. */ > > + if (in_serving_softirq()) > > + return NULL; > > + > > + if (WARN_ON_ONCE(in_nmi() || in_hardirq())) > > + return NULL; > > WARN does a lot of stuff and I rather doubt that it's all nmi-safe. I > don't think this matters much - it'll probably work out and as long as > *something* gets printed, it did its job. > Yep. I checked before the kernel sources and saw that people use it with WARN. I thought switching from BUG() to WARN() is better. -- Uladzislau Rezki