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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48febf86db7sm155106115e9.6.2026.05.19.03.02.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 May 2026 03:02:25 -0700 (PDT) Date: Tue, 19 May 2026 11:02:23 +0100 From: David Laight To: Tony Rodriguez Cc: davem@davemloft.net, sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, andreas@gaisler.com, thuth@redhat.com, regressions@lists.linux.dev, glaubitz@physik.fu-berlin.de Subject: Re: [PATCH 0/1] sparc64: unify thread stack sizing and add explicit 32KB stack Message-ID: <20260519110223.5aeb88e3@pumpkin> In-Reply-To: <20260519075809.8993-1-unixpro1970@gmail.com> References: <20260519075809.8993-1-unixpro1970@gmail.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Tue, 19 May 2026 00:57:54 -0700 Tony Rodriguez wrote: > This patch fixes a reproducible stack exhaustion issue on SPARC64 > that occurs during USB hub enumeration. This regression may have > started sometime after kernel v6.12. With the default 16KB kernel > stack, the following panic is triggered early in boot: >=20 > [ 25.528399] Call Trace: > [ 25.528403] [<0000000000433cd4>] dump_stack+0x8/0x18 > [ 25.528419] [<00000000004297ac>] vpanic+0xdc/0x318 > [ 25.528429] [<0000000000429a0c>] panic+0x24/0x30 > [ 25.528436] [<0000000000be2280>] __schedule+0xa8/0x7bc > [ 25.528445] [<0000000000be2b60>] schedule+0x24/0x4c > [ 25.528452] [<0000000000be6970>] schedule_timeout+0xc8/0xe4 > [ 25.528459] [<0000000000be3318>] __wait_for_common+0x78/0xf0 > [ 25.528466] [<0000000000be3550>] wait_for_completion_timeout+0x1c/= 0x2c > [ 25.528473] [<000000001005e2f4>] usb_start_wait_urb+0x68/0x128 [us= bcore] > [ 25.528502] [<000000001005e468>] usb_control_msg+0xb4/0xf8 [usbcor= e] > [ 25.528518] [<0000000010051180>] set_port_feature+0x44/0x54 [usbco= re] > [ 25.528530] [<00000000100530f0>] hub_power_on+0xc8/0xe8 [usbcore] > [ 25.528543] [<0000000010054fd8>] hub_activate+0x12c/0x644 [usbcore] > [ 25.528557] [<0000000010059438>] hub_probe+0xdd4/0xeb0 [usbcore] > [ 25.528570] [<0000000010062360>] usb_probe_interface+0x234/0x26c [= usbcore] > [ 25.528585] [<0000000000a10a40>] really_probe+0x1ac/0x3b0 >=20 > This is caused by large SPARC64 trapframes, register-window spills, > and deep call paths in usbcore. A 16KB stack is insufficient for > this workload. Increasing the stack size for all threads seems overkill. That stack doesn't even look deep. I suspect there are large on-stack buffers in there. Unfortunately the traceback doesn't print the stack pointers making debugging hard. -- David >=20 > The new logic is: >=20 > SPARC64: > THREAD_SIZE =3D 4 * PAGE_SIZE (32KB) > THREAD_SHIFT =3D PAGE_SHIFT + 2 > THREAD_SIZE_ORDER =3D 2 >=20 > Non=E2=80=91SPARC64 with PAGE_SHIFT =3D=3D 13: > Retains the existing 16KB stack behavior >=20 > Fallback: > Retains the existing 8KB stack behavior >=20 > Signed-off-by: Tony Rodriguez >=20 >=20 > Tony Rodriguez (1): > sparc64: unify thread stack sizing and add explicit 32KB stack >=20 > arch/sparc/include/asm/thread_info_64.h | 28 ++++++++++++------------- > 1 file changed, 14 insertions(+), 14 deletions(-) >=20 > -- > 2.53.0 >=20 >=20