From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 598836AB9 for ; Wed, 23 Mar 2022 23:06:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 224FAC340E8; Wed, 23 Mar 2022 23:06:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1648076812; bh=fuOGKRKSSVApUKrrDtWBJXdPhJs/H587LuUnAeOtRZ0=; h=Date:To:From:In-Reply-To:Subject:From; b=L39T/rhn+DSYaf/tD/+3Gb6gRzcaVA9t0I2I0dIB9r7e/h5sNMHYGEV1km1A/PZ3f 4mUdsjkal2M9SygQTvniMU+PwQUgwdVhr5epMkMPeYy3jGs0Hb00+Xbc36bBBpnwND Y30kutLNDg+rd0ahUw7e7SQmL9N65T8b79wO5B60= Date: Wed, 23 Mar 2022 16:06:51 -0700 To: ryabinin.a.a@gmail.com,lixuefeng@loongson.cn,elver@google.com,corbet@lwn.net,bhe@redhat.com,yangtiezhu@loongson.cn,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220323160453.65922ced539cbf445b191555@linux-foundation.org> Subject: [patch 31/41] panic: unset panic_on_warn inside panic() Message-Id: <20220323230652.224FAC340E8@smtp.kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: From: Tiezhu Yang Subject: panic: unset panic_on_warn inside panic() In the current code, the following three places need to unset panic_on_warn before calling panic() to avoid recursive panics: kernel/kcsan/report.c: print_report() kernel/sched/core.c: __schedule_bug() mm/kfence/report.c: kfence_report_error() In order to avoid copy-pasting "panic_on_warn = 0" all over the places, it is better to move it inside panic() and then remove it from the other places. Link: https://lkml.kernel.org/r/1644324666-15947-4-git-send-email-yangtiezhu@loongson.cn Signed-off-by: Tiezhu Yang Reviewed-by: Marco Elver Cc: Andrey Ryabinin Cc: Baoquan He Cc: Jonathan Corbet Cc: Xuefeng Li Signed-off-by: Andrew Morton --- kernel/panic.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) --- a/kernel/panic.c~panic-unset-panic_on_warn-inside-panic +++ a/kernel/panic.c @@ -185,6 +185,16 @@ void panic(const char *fmt, ...) int old_cpu, this_cpu; bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers; + if (panic_on_warn) { + /* + * This thread may hit another WARN() in the panic path. + * Resetting this prevents additional WARN() from panicking the + * system on this thread. Other threads are blocked by the + * panic_mutex in panic(). + */ + panic_on_warn = 0; + } + /* * Disable local interrupts. This will prevent panic_smp_self_stop * from deadlocking the first cpu that invokes the panic, since @@ -576,16 +586,8 @@ void __warn(const char *file, int line, if (regs) show_regs(regs); - if (panic_on_warn) { - /* - * This thread may hit another WARN() in the panic path. - * Resetting this prevents additional WARN() from panicking the - * system on this thread. Other threads are blocked by the - * panic_mutex in panic(). - */ - panic_on_warn = 0; + if (panic_on_warn) panic("panic_on_warn set ...\n"); - } if (!regs) dump_stack(); _