From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by merlin.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1coUVx-0003b1-Am for kexec@lists.infradead.org; Thu, 16 Mar 2017 12:28:21 +0000 Date: Thu, 16 Mar 2017 20:27:30 +0800 From: Baoquan He Subject: Re: [PATCH] kexec: Update vmcoreinfo after crash happened Message-ID: <20170316122730.GB23625@x1> References: <1489666587-24103-1-git-send-email-xlpang@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1489666587-24103-1-git-send-email-xlpang@redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Xunlei Pang Cc: Dave Young , akpm@linux-foundation.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Eric Biederman Hi Xunlei, Did you really see this ever happened? Because the vmcore size estimate feature, namely --mem-usage option of makedumpfile, depends on the vmcoreinfo in 1st kernel, your change will break it. If not, it could be not good to change that. Baoquan On 03/16/17 at 08:16pm, Xunlei Pang wrote: > Currently vmcoreinfo data is updated at boot time subsys_initcall(), > it has the risk of being modified by some wrong code during system > is running. > > As a result, vmcore dumped will contain the wrong vmcoreinfo. Later on, > when using "crash" utility to parse this vmcore, we probably will get > "Segmentation fault". > > Based on the fact that the value of each vmcoreinfo stays invariable > once kernel boots up, we safely move all the vmcoreinfo operations into > crash_save_vmcoreinfo() which is called after crash happened. In this > way, vmcoreinfo data correctness is always guaranteed. > > Signed-off-by: Xunlei Pang > --- > kernel/kexec_core.c | 14 +++----------- > 1 file changed, 3 insertions(+), 11 deletions(-) > > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c > index bfe62d5..1bfdd96 100644 > --- a/kernel/kexec_core.c > +++ b/kernel/kexec_core.c > @@ -1367,12 +1367,6 @@ static void update_vmcoreinfo_note(void) > final_note(buf); > } > > -void crash_save_vmcoreinfo(void) > -{ > - vmcoreinfo_append_str("CRASHTIME=%ld\n", get_seconds()); > - update_vmcoreinfo_note(); > -} > - > void vmcoreinfo_append_str(const char *fmt, ...) > { > va_list args; > @@ -1402,7 +1396,7 @@ phys_addr_t __weak paddr_vmcoreinfo_note(void) > return __pa_symbol((unsigned long)(char *)&vmcoreinfo_note); > } > > -static int __init crash_save_vmcoreinfo_init(void) > +void crash_save_vmcoreinfo(void) > { > VMCOREINFO_OSRELEASE(init_uts_ns.name.release); > VMCOREINFO_PAGESIZE(PAGE_SIZE); > @@ -1474,13 +1468,11 @@ static int __init crash_save_vmcoreinfo_init(void) > #endif > > arch_crash_save_vmcoreinfo(); > - update_vmcoreinfo_note(); > + vmcoreinfo_append_str("CRASHTIME=%ld\n", get_seconds()); > > - return 0; > + update_vmcoreinfo_note(); > } > > -subsys_initcall(crash_save_vmcoreinfo_init); > - > /* > * Move into place and start executing a preloaded standalone > * executable. If nothing was preloaded return an error. > -- > 1.8.3.1 > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec