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[2a02:3100:a133:e401:bc8e:d36c:2d08:c5e0]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-499788a6cdfsm21958995e9.6.2026.08.11.02.55.37 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 11 Aug 2026 02:55:37 -0700 (PDT) From: Karl Mehltretter To: Marc Zyngier , Thomas Gleixner Cc: Karl Mehltretter , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, syzbot+229d761b8a110e6de517@syzkaller.appspotmail.com Subject: [PATCH] irqchip/gic-v3-its: Don't WARN on LPI free allocation failure Date: Tue, 11 Aug 2026 11:55:32 +0200 Message-Id: <20260811095532.48454-1-kmehltretter@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <564b7035-7d20-4f5b-ac7d-a48e58e4a0a0@mail.kernel.org> References: <564b7035-7d20-4f5b-ac7d-a48e58e4a0a0@mail.kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" free_lpi_range() cannot give LPIs back to the allocator without allocating a struct lpi_range to describe the freed range, so it returns -ENOMEM (its only failure mode) when that allocation fails, and its_lpi_free() turns this into a WARN_ON(). syzbot triggers the WARN_ON() by injecting a slab allocation failure on device teardown, which with panic_on_warn becomes a panic: WARNING: drivers/irqchip/irq-gic-v3-its.c:2251 at its_msi_teardown+0x3a4/= 0x424 its_msi_teardown+0x3a4/0x424 msi_remove_device_irq_domain+0x16c/0x27c msi_device_data_release+0x38/0x9c The failure is transient and the consequence benign: the freed range is simply never returned to the allocator. This does not warrant a WARN_ON() backtrace, so log a rate-limited error instead. Fixes: 880cb3cddd16 ("irqchip/gic-v3-its: Refactor LPI allocator") Reported-by: syzbot+229d761b8a110e6de517@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D229d761b8a110e6de517 Assisted-by: Claude:claude-fable-5 Signed-off-by: Karl Mehltretter --- drivers/irqchip/irq-gic-v3-its.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-= its.c index 6f5811aae59c1..5ab278affa9dd 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -2248,7 +2248,8 @@ static unsigned long *its_lpi_alloc(int nr_irqs, u32 = *base, int *nr_ids) =20 static void its_lpi_free(unsigned long *bitmap, u32 base, u32 nr_ids) { - WARN_ON(free_lpi_range(base, nr_ids)); + if (free_lpi_range(base, nr_ids)) + pr_err_ratelimited("ITS: failed to free LPI range %u:%u\n", base, nr_ids= ); bitmap_free(bitmap); } =20 --=20 2.53.0