Messages in this thread | ![/](/images/icornerl.gif) | | Date | Sat, 13 Apr 2024 21:57:40 +0800 | From | Baoquan He <> | Subject | Re: [PATCH v2] kexec: fix the unexpected kexec_dprintk() macro |
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On 04/12/24 at 03:28pm, Dave Young wrote: > On Tue, 9 Apr 2024 at 12:23, Baoquan He <bhe@redhat.com> wrote: > > > > Jiri reported that the current kexec_dprintk() always prints out > > debugging message whenever kexec/kdmmp loading is triggered. That is > > not wanted. The debugging message is supposed to be printed out when > > 'kexec -s -d' is specified for kexec/kdump loading. > > > > After investigating, the reason is the current kexec_dprintk() takes > > printk(KERN_INFO) or printk(KERN_DEBUG) depending on whether '-d' is > > specified. However, distros usually have defaulg log level like below: > > > > [~]# cat /proc/sys/kernel/printk > > 7 4 1 7 > > > > So, even though '-d' is not specified, printk(KERN_DEBUG) also always > > prints out. I thought printk(KERN_DEBUG) is equal to pr_debug(), it's > > not. > > > > Fix it by changing to use pr_info() instead which are expected to work. > > Could you also update the kernel/crash_core.c and > kernel/crash_reserve.c to include the filename prefix? > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
OK, thanks for testing and spotting this.
When I tested this patch, I only did test kexec reboot functionality. So the line of printing in kernel/crash_core.c is missed. While there seems to be no kexec_dprintk() in kernel/crash_reserve.c. Anyway, adding pr_fmt() is a good idea for debug printing in that file. I will post a standalone patch to add these.
> > Otherwise: > Reviewed-by: Dave Young <dyoung@redhat.com>
Thanks again.
> > > > > Fixes: cbc2fe9d9cb2 ("kexec_file: add kexec_file flag to control debug printing") > > Signed-off-by: Baoquan He <bhe@redhat.com> > > Reported-by: Jiri Slaby <jirislaby@kernel.org> > > Closes: https://lore.kernel.org/all/4c775fca-5def-4a2d-8437-7130b02722a2@kernel.org > > --- > > v1->v2: > > - Change to use pr_info() only when "kexec -s -d" is specified. With > > this change, those debugging message for "kexec -c -d" of kexec_load > > will be missed. We'll see if we need add them for kexec_load too, if > > someone explicitly requests it. > > > > include/linux/kexec.h | 6 ++---- > > 1 file changed, 2 insertions(+), 4 deletions(-) > > > > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > > index 060835bb82d5..f31bd304df45 100644 > > --- a/include/linux/kexec.h > > +++ b/include/linux/kexec.h > > @@ -461,10 +461,8 @@ static inline void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages) { > > > > extern bool kexec_file_dbg_print; > > > > -#define kexec_dprintk(fmt, ...) \ > > - printk("%s" fmt, \ > > - kexec_file_dbg_print ? KERN_INFO : KERN_DEBUG, \ > > - ##__VA_ARGS__) > > +#define kexec_dprintk(fmt, arg...) \ > > + do { if (kexec_file_dbg_print) pr_info(fmt, ##arg); } while (0) > > > > #else /* !CONFIG_KEXEC_CORE */ > > struct pt_regs; > > -- > > 2.41.0 > > > > >
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