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Tue, 27 Oct 2026 00:57:06 +0000 X-Mizu-Trace-ID: 12bbfc182f6c0f69 X-Migadu-Flow: FLOW_OUT Date: Tue, 27 Oct 2026 08:57:02 +0800 From: Baoquan He To: "Uladzislau Rezki (Sony)" Cc: linux-mm@kvack.org, Andrew Morton , LKML , "David Hildenbrand (Arm)" Subject: Re: [PATCH] mm/vmalloc: Bail out if in softirq context Message-ID: References: <20261026102503.30860-1-urezki@gmail.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261026102503.30860-1-urezki@gmail.com> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: A628B180003 X-Stat-Signature: 1nb5kbjrou631qfb9rr8d4hykc6e9gws X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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: 1793062627-897314 X-HE-Meta: U2FsdGVkX18n69qwJsRFSL0Ra3X5t0u7moZH6zUBXjfscNCNk7mlPt08GRsRrKMULT3/CJZiD7pDcqGeuw/B302RAQr6af048S3T53nkVDiApGL24K6b+iIe6ZmG8IKSxflE13DGBZ745GeRqhMmGut36nc0rmui0gJHFQjf/X6FKixwWW60n/lvdGnJaBWx2gol5TKEPSXvbHzA741Vob03LsN19IALJh8Z3pxqUNLEGmsb/l8ggU7YwlKjtxunkhtpzYF/qRaof5l7M6G6PbFY3cRIQkMbDNQEmRtZWpf9CCxiZhD/i3JpThuydeYNb2KCj/xPOG3w7qaY1jkTpHPdrWYUD0gSfXQ5e6hgnF9wSc0ClsjNurRtCfZSbKxRw2eMS6oI7ZoTpgXaL1CATxZQdBtt5dJx8+ux/rGoB0IyrEsgmayCwB3A8u/uYeatOv+M5Sz5cRR5ObIgFxkW3sfSWU8qwL5wGsjtFMltczukGrykz1CZOQX6Myyi3zeT6gb9kxOYekiHf4pR6Z8O/gi9IogH1aOXyurUdLTxW6KYCvipjFp4i1OTvCmm9AKm4jIbRWoN5JrPkVFKEs5t8cD5fTmKrJmOLcokQi0JBHflScDCGlsh5MK2ZTkNyouwCC6r4ZHd7Thd8EayetTn7krvtFIv1BLO66sJgQRRh44V4hgGU522J1apBZzvNTuxD8loTnK7/I2e3Q0Cb6LzpCSkg8WABpN1wK/rGPzjOHpBtObEsUOISW3St9/OxhhTr6rGQ0iWI4RsFnb0B9cJDW3rKa9NkGtQy83u/lwKuWkcmzKEmo55Xi2YmOKwTLPfKelFauKUMusF2c52gNKJyBwAW2kjA1fQzg50L3vV3WlSjhx7MkSrlD7sUECyYL3GeCRJSoiJuSt3AgKCVAkxpQq3IkQQw+mOqa++3dgAyg2tqFUYNMaPVsm065QxYBkMte80BMjjL2KmoA6x6AG ym9lS2t4 RtYFkQHhE7f76S5X9a0+PP9HfBzZl/yjXCyapLhOtUroD+PVnUrQoFyPdFIHiOzX3+vUN70K8zC5/3FSMQO3DmHeWf00E/1GLiAgRjMNrNIoGJCLrqnqQ/AkSAmDa03d7Gq4oT9DoLLEimRzP+sPpCe8NQAvC1v5RcBj80O8z2jp5R/2ZXTgq1aTXML0VpL8C/0JKoxcP9Z2rUkCpXlr7RASJeasoqnFf2NYF7UbjEOFr8M+6r01HRw13gea3K1NpKsavg0cFEASlavqaSIm5hkxDR2DwGUzkloHyGChFW9xNPae6KhyAyv4dcA== 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 10/26/26 at 11:25am, 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") > 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; > + LGTM, Reviewed-by: Baoquan He > size = ALIGN(size, 1ul << shift); > if (unlikely(!size)) > return NULL; > -- > 2.47.3 >