Re: [PATCH V2] kernel, add bug_on_warn
On 10/30/2014 08:25 PM, Rusty Russell wrote:
> Prarit Bhargava writes:
>> On 10/22/2014 12:27 AM, Rusty Russell wrote:
>>> Prarit Bhargava writes:
There have been several times where I have had to rebuild a kernel to
cause a panic when hitting a WARN() in the code in order to get a crash
dump from a system. Sometimes this is easy to do, other times (such as
in the case of a remote admin) it is not trivial to send new images to the
user.
>>>
>>> What about during early boot?
>>
>> Hi Rusty,
>>
>> I really don't have a use case for this in early boot. The kernel boots, the
>> initramfs, and then we run whatever init (systemd in my case). A systemd
>> script
>> configures kexec for kdump and that point kdump is "armed". Doing a
>> bug_on_warn
>> before this will simply result in a panicked system. I don't get any "new"
>> information FWIW as I get a stack trace, etc., in both the WARN() and BUG()
>> cases.
>>
>>>
>>> I'd recommend you use core_param(). Less code, and can be set on
>>> commandline.
Yeah, I was just starting to do this and then I saw Hedi's comment about
disabling panic_on_warn during kdump to avoid a situation where the kdump kernel
bogus panics on a warn.
So that makes the setup function look like:
static int __init panic_on_warn_setup(char *s)
{
/* Enabling this on a kdump kernel could cause a bogus panic. */
if (!is_kdump_kernel())
panic_on_warn = 1;
return 0;
}
early_param("panic_on_warn", panic_on_warn_setup);
... so I dunno if core_param would work here :(. It would have been nice if it
did.
P.
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Re: [PATCH V2] kernel, add bug_on_warn
Prarit Bhargava writes:
> On 10/22/2014 12:27 AM, Rusty Russell wrote:
>> Prarit Bhargava writes:
>>> There have been several times where I have had to rebuild a kernel to
>>> cause a panic when hitting a WARN() in the code in order to get a crash
>>> dump from a system. Sometimes this is easy to do, other times (such as
>>> in the case of a remote admin) it is not trivial to send new images to the
>>> user.
>>
>> What about during early boot?
>
> Hi Rusty,
>
> I really don't have a use case for this in early boot. The kernel boots, the
> initramfs, and then we run whatever init (systemd in my case). A systemd
> script
> configures kexec for kdump and that point kdump is "armed". Doing a
> bug_on_warn
> before this will simply result in a panicked system. I don't get any "new"
> information FWIW as I get a stack trace, etc., in both the WARN() and BUG()
> cases.
>
>>
>> I'd recommend you use core_param(). Less code, and can be set on
>> commandline.
>
> Is that a general request, or is it dependent on the answer above? Of course
> I
> have no problem doing it either way.
Oops, I read your initial patch too lightly: I see you added both
a sysctl (which I saw) and an early_param (which I didn't).
I still think it should be a core_param, like so (untested!):
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 6c0b9f27e465..cf16cbe9f544 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -471,6 +471,13 @@ format. Crash is available on Dave Anderson's site at the
following URL:
http://people.redhat.com/~anderson/
+Trigger Kdump on WARN()
+===
+
+The kernel parameter, bug_on_warn, calls BUG() in all WARN() paths. This
+will cause a kdump to occur at the BUG() call. In cases where a user
+wants to specify this during runtime, /sys/module/kernel/bug_on_warn can be
+set to 1 to achieve the same behaviour.
Contact
===
diff --git a/Documentation/kernel-parameters.txt
b/Documentation/kernel-parameters.txt
index 74339c57b914..aa1d3198e987 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -553,6 +553,9 @@ bytes respectively. Such letter suffixes can also be
entirely omitted.
bttv.pll= See Documentation/video4linux/bttv/Insmod-options
bttv.tuner=
+ bug_on_warn BUG() instead of WARN(). Useful to cause kdump
+ on a WARN().
+
bulk_remove=off [PPC] This parameter disables the use of the pSeries
firmware feature for flushing multiple hpte entries
at a time.
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 630dd2372238..4d0c763862b0 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -75,10 +75,18 @@ extern void warn_slowpath_null(const char *file, const int
line);
#define __WARN_printf_taint(taint, arg...) \
warn_slowpath_fmt_taint(__FILE__, __LINE__, taint, arg)
#else
-#define __WARN() __WARN_TAINT(TAINT_WARN)
+#define check_bug_on_warn()\
+ do {\
+ if (bug_on_warn)\
+ BUG(); \
+ } while (0)
+
+#define __WARN() \
+ do { __WARN_TAINT(TAINT_WARN); check_bug_on_warn(); } while (0)
+
#define __WARN_printf(arg...) do { printk(arg); __WARN(); } while (0)
#define __WARN_printf_taint(taint, arg...) \
- do { printk(arg); __WARN_TAINT(taint); } while (0)
+ do { printk(arg); __WARN_TAINT(taint); check_bug_on_warn(); } while (0)
#endif
#ifndef WARN_ON
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 3d770f5564b8..d583df09ee82 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -423,6 +423,7 @@ extern int panic_on_oops;
extern int panic_on_unrecovered_nmi;
extern int panic_on_io_nmi;
extern int sysctl_panic_on_stackoverflow;
+extern bool bug_on_warn;
/*
* Only to be used by arch init code. If the user over-wrote the default
* CONFIG_PANIC_TIMEOUT, honor it.
diff --git a/kernel/panic.c b/kernel/panic.c
index d09dc5c32c67..3d345357fcc8 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -33,6 +33,7 @@ static int pause_on_oops;
static int pause_on_oops_flag;
static DEFINE_SPINLOCK(pause_on_oops_lock);
static bool crash_kexec_post_notifiers;
+bool bug_on_warn;
int panic_timeout = CONFIG_PANIC_TIMEOUT;
EXPORT_SYMBOL_GPL(panic_timeout);
@@ -420,13 +421,24 @@ static void warn_slowpath_common(const char *file, int
line, void *caller,
{
disable_trace_on_warning();
- pr_warn("[ cut here ]\n");
+ if (!bug_on_warn)
+ pr_warn("[
Re: [PATCH V2] kernel, add bug_on_warn
(2014/10/22 1:47), Prarit Bhargava wrote: > There have been several times where I have had to rebuild a kernel to > cause a panic when hitting a WARN() in the code in order to get a crash > dump from a system. Sometimes this is easy to do, other times (such as > in the case of a remote admin) it is not trivial to send new images to the > user. > > A much easier method would be a switch to change the WARN() over to a > BUG(). This makes debugging easier in that I can now test the actual > image the WARN() was seen on and I do not have to engage in remote > debugging. > > This patch adds a bug_on_warn kernel parameter, which calls BUG() in the > warn_slowpath_common() path. The function will still print out the > location of the warning. > > An example of the bug_on_warn output: > > The first line below is from the WARN_ON() to output the WARN_ON()'s location. > After that the new BUG() call is displayed. > > WARNING: CPU: 27 PID: 3204 at > /home/rhel7/redhat/debug/dummy-module/dummy-module.c:25 init_dummy+0x28/0x30 > [dummy_module]() > bug_on_warn set, calling BUG()... > [ cut here ] > kernel BUG at kernel/panic.c:434! > invalid opcode: [#1] SMP > Modules linked in: dummy_module(OE+) sg nfsv3 rpcsec_gss_krb5 nfsv4 > dns_resolver nfs fscache cfg80211 rfkill x86_pkg_temp_thermal intel_powerclamp > coretemp kvm_intel kvm crct10dif_pclmul crc32_pclmul crc32c_intel > ghash_clmulni_intel igb iTCO_wdt aesni_intel iTCO_vendor_support lrw gf128mul > sb_edac ptp edac_core glue_helper lpc_ich ioatdma pcspkr ablk_helper pps_core > i2c_i801 mfd_core cryptd dca shpchp ipmi_si wmi ipmi_msghandler acpi_cpufreq > nfsd auth_rpcgss nfs_acl lockd grace sunrpc xfs libcrc32c sr_mod cdrom sd_mod > mgag200 syscopyarea sysfillrect sysimgblt i2c_algo_bit drm_kms_helper isci ttm > drm libsas ahci libahci scsi_transport_sas libata i2c_core dm_mirror > dm_region_hash dm_log dm_mod > CPU: 27 PID: 3204 Comm: insmod Tainted: G OE 3.17.0+ #19 > Hardware name: Intel Corporation S2600CP/S2600CP, BIOS > RMLSDP.86I.00.29.D696.131329 11/11/2013 > task: 880034e75160 ti: 8807fc5ac000 task.ti: 8807fc5ac000 > RIP: 0010:[] [] > warn_slowpath_common+0xc1/0xd0 > RSP: 0018:8807fc5afc68 EFLAGS: 00010246 > RAX: 0021 RBX: 8807fc5afcb0 RCX: > RDX: RSI: 88081efee5f8 RDI: 88081efee5f8 > RBP: 8807fc5afc98 R08: 0096 R09: > R10: 0711 R11: 8807fc5af93e R12: a0424070 > R13: 0019 R14: a0423068 R15: 0009 > FS: 7f2d4b034740() GS:88081efe() knlGS: > CS: 0010 DS: ES: CR0: 80050033 > CR2: 7f2d4a99f3c0 CR3: 0007fd88b000 CR4: 001407e0 > Stack: >8807fc5afcb8 8199f020 88080e396160 >a0423040 a0425000 8807fc5afd08 81076be5 >0008 a0424053 88070018 8807fc5afd18 > Call Trace: >[] ? dummy_greetings+0x40/0x40 [dummy_module] >[] warn_slowpath_fmt+0x55/0x70 >[] init_dummy+0x28/0x30 [dummy_module] >[] do_one_initcall+0xd4/0x210 >[] ? __vunmap+0xc2/0x110 >[] load_module+0x16a9/0x1b30 >[] ? store_uevent+0x70/0x70 >[] ? copy_module_from_fd.isra.44+0x129/0x180 >[] SyS_finit_module+0xa6/0xd0 >[] system_call_fastpath+0x12/0x17 > Code: c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 48 c7 c7 20 42 8a 81 31 c0 e8 > fc > 80 5e 00 eb 80 48 c7 c7 78 42 8a 81 31 c0 e8 ec 80 5e 00 <0f> 0b 66 66 66 66 > 2e > 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 > RIP [] warn_slowpath_common+0xc1/0xd0 >RSP > ---[ end trace 428218934a12088b ]--- > > Successfully tested by me. > > Cc: Jonathan Corbet > Cc: Andrew Morton > Cc: Rusty Russell > Cc: "H. Peter Anvin" > Cc: Andi Kleen > Cc: Masami Hiramatsu > Cc: Fabian Frederick > Cc: vgo...@redhat.com > Cc: isimatu.yasu...@jp.fujitsu.com > Cc: linux-...@vger.kernel.org > Cc: ke...@lists.infradead.org > Cc: linux-...@vger.kernel.org > Signed-off-by: Prarit Bhargava > > [v2]: add /proc/sys/kernel/bug_on_warn, additional documentation, modify >!slowpath cases > --- > Documentation/kdump/kdump.txt |7 +++ > Documentation/kernel-parameters.txt |3 +++ > Documentation/sysctl/kernel.txt | 12 > include/asm-generic/bug.h | 12 ++-- > include/linux/kernel.h |1 + > include/uapi/linux/sysctl.h |1 + > kernel/panic.c | 21 - > kernel/sysctl.c |7 +++ > kernel/sysctl_binary.c |1 + > 9 files changed, 62 insertions(+), 3 deletions(-) > > diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt > index 6c0b9f2..a04ed72 100644 > --- a/Documentation/kdump/kdump.txt > +++ b/Documentation/kd
Re: [PATCH V2] kernel, add bug_on_warn
On 10/22/2014 12:27 AM, Rusty Russell wrote: > Prarit Bhargava writes: >> There have been several times where I have had to rebuild a kernel to >> cause a panic when hitting a WARN() in the code in order to get a crash >> dump from a system. Sometimes this is easy to do, other times (such as >> in the case of a remote admin) it is not trivial to send new images to the >> user. >> >> A much easier method would be a switch to change the WARN() over to a >> BUG(). This makes debugging easier in that I can now test the actual >> image the WARN() was seen on and I do not have to engage in remote >> debugging. >> >> This patch adds a bug_on_warn kernel parameter, which calls BUG() in the >> warn_slowpath_common() path. The function will still print out the >> location of the warning. >> >> An example of the bug_on_warn output: >> >> The first line below is from the WARN_ON() to output the WARN_ON()'s >> location. >> After that the new BUG() call is displayed. >> >> WARNING: CPU: 27 PID: 3204 at >> /home/rhel7/redhat/debug/dummy-module/dummy-module.c:25 init_dummy+0x28/0x30 >> [dummy_module]() >> bug_on_warn set, calling BUG()... >> [ cut here ] >> kernel BUG at kernel/panic.c:434! >> invalid opcode: [#1] SMP >> Modules linked in: dummy_module(OE+) sg nfsv3 rpcsec_gss_krb5 nfsv4 >> dns_resolver nfs fscache cfg80211 rfkill x86_pkg_temp_thermal >> intel_powerclamp >> coretemp kvm_intel kvm crct10dif_pclmul crc32_pclmul crc32c_intel >> ghash_clmulni_intel igb iTCO_wdt aesni_intel iTCO_vendor_support lrw gf128mul >> sb_edac ptp edac_core glue_helper lpc_ich ioatdma pcspkr ablk_helper pps_core >> i2c_i801 mfd_core cryptd dca shpchp ipmi_si wmi ipmi_msghandler acpi_cpufreq >> nfsd auth_rpcgss nfs_acl lockd grace sunrpc xfs libcrc32c sr_mod cdrom sd_mod >> mgag200 syscopyarea sysfillrect sysimgblt i2c_algo_bit drm_kms_helper isci >> ttm >> drm libsas ahci libahci scsi_transport_sas libata i2c_core dm_mirror >> dm_region_hash dm_log dm_mod >> CPU: 27 PID: 3204 Comm: insmod Tainted: G OE 3.17.0+ #19 >> Hardware name: Intel Corporation S2600CP/S2600CP, BIOS >> RMLSDP.86I.00.29.D696.131329 11/11/2013 >> task: 880034e75160 ti: 8807fc5ac000 task.ti: 8807fc5ac000 >> RIP: 0010:[] [] >> warn_slowpath_common+0xc1/0xd0 >> RSP: 0018:8807fc5afc68 EFLAGS: 00010246 >> RAX: 0021 RBX: 8807fc5afcb0 RCX: >> RDX: RSI: 88081efee5f8 RDI: 88081efee5f8 >> RBP: 8807fc5afc98 R08: 0096 R09: >> R10: 0711 R11: 8807fc5af93e R12: a0424070 >> R13: 0019 R14: a0423068 R15: 0009 >> FS: 7f2d4b034740() GS:88081efe() knlGS: >> CS: 0010 DS: ES: CR0: 80050033 >> CR2: 7f2d4a99f3c0 CR3: 0007fd88b000 CR4: 001407e0 >> Stack: >> 8807fc5afcb8 8199f020 88080e396160 >> a0423040 a0425000 8807fc5afd08 81076be5 >> 0008 a0424053 88070018 8807fc5afd18 >> Call Trace: >> [] ? dummy_greetings+0x40/0x40 [dummy_module] >> [] warn_slowpath_fmt+0x55/0x70 >> [] init_dummy+0x28/0x30 [dummy_module] >> [] do_one_initcall+0xd4/0x210 >> [] ? __vunmap+0xc2/0x110 >> [] load_module+0x16a9/0x1b30 >> [] ? store_uevent+0x70/0x70 >> [] ? copy_module_from_fd.isra.44+0x129/0x180 >> [] SyS_finit_module+0xa6/0xd0 >> [] system_call_fastpath+0x12/0x17 >> Code: c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 48 c7 c7 20 42 8a 81 31 c0 e8 >> fc >> 80 5e 00 eb 80 48 c7 c7 78 42 8a 81 31 c0 e8 ec 80 5e 00 <0f> 0b 66 66 66 66 >> 2e >> 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 >> RIP [] warn_slowpath_common+0xc1/0xd0 >> RSP >> ---[ end trace 428218934a12088b ]--- >> >> Successfully tested by me. >> >> Cc: Jonathan Corbet >> Cc: Andrew Morton >> Cc: Rusty Russell >> Cc: "H. Peter Anvin" >> Cc: Andi Kleen >> Cc: Masami Hiramatsu >> Cc: Fabian Frederick >> Cc: vgo...@redhat.com >> Cc: isimatu.yasu...@jp.fujitsu.com >> Cc: linux-...@vger.kernel.org >> Cc: ke...@lists.infradead.org >> Cc: linux-...@vger.kernel.org >> Signed-off-by: Prarit Bhargava >> >> [v2]: add /proc/sys/kernel/bug_on_warn, additional documentation, modify >> !slowpath cases >> --- >> Documentation/kdump/kdump.txt |7 +++ >> Documentation/kernel-parameters.txt |3 +++ >> Documentation/sysctl/kernel.txt | 12 >> include/asm-generic/bug.h | 12 ++-- >> include/linux/kernel.h |1 + >> include/uapi/linux/sysctl.h |1 + >> kernel/panic.c | 21 - >> kernel/sysctl.c |7 +++ >> kernel/sysctl_binary.c |1 + >> 9 files changed, 62 insertions(+), 3 deletions(-) >> >> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt >
Re: [PATCH V2] kernel, add bug_on_warn
Prarit Bhargava writes: > There have been several times where I have had to rebuild a kernel to > cause a panic when hitting a WARN() in the code in order to get a crash > dump from a system. Sometimes this is easy to do, other times (such as > in the case of a remote admin) it is not trivial to send new images to the > user. > > A much easier method would be a switch to change the WARN() over to a > BUG(). This makes debugging easier in that I can now test the actual > image the WARN() was seen on and I do not have to engage in remote > debugging. > > This patch adds a bug_on_warn kernel parameter, which calls BUG() in the > warn_slowpath_common() path. The function will still print out the > location of the warning. > > An example of the bug_on_warn output: > > The first line below is from the WARN_ON() to output the WARN_ON()'s location. > After that the new BUG() call is displayed. > > WARNING: CPU: 27 PID: 3204 at > /home/rhel7/redhat/debug/dummy-module/dummy-module.c:25 init_dummy+0x28/0x30 > [dummy_module]() > bug_on_warn set, calling BUG()... > [ cut here ] > kernel BUG at kernel/panic.c:434! > invalid opcode: [#1] SMP > Modules linked in: dummy_module(OE+) sg nfsv3 rpcsec_gss_krb5 nfsv4 > dns_resolver nfs fscache cfg80211 rfkill x86_pkg_temp_thermal intel_powerclamp > coretemp kvm_intel kvm crct10dif_pclmul crc32_pclmul crc32c_intel > ghash_clmulni_intel igb iTCO_wdt aesni_intel iTCO_vendor_support lrw gf128mul > sb_edac ptp edac_core glue_helper lpc_ich ioatdma pcspkr ablk_helper pps_core > i2c_i801 mfd_core cryptd dca shpchp ipmi_si wmi ipmi_msghandler acpi_cpufreq > nfsd auth_rpcgss nfs_acl lockd grace sunrpc xfs libcrc32c sr_mod cdrom sd_mod > mgag200 syscopyarea sysfillrect sysimgblt i2c_algo_bit drm_kms_helper isci ttm > drm libsas ahci libahci scsi_transport_sas libata i2c_core dm_mirror > dm_region_hash dm_log dm_mod > CPU: 27 PID: 3204 Comm: insmod Tainted: G OE 3.17.0+ #19 > Hardware name: Intel Corporation S2600CP/S2600CP, BIOS > RMLSDP.86I.00.29.D696.131329 11/11/2013 > task: 880034e75160 ti: 8807fc5ac000 task.ti: 8807fc5ac000 > RIP: 0010:[] [] > warn_slowpath_common+0xc1/0xd0 > RSP: 0018:8807fc5afc68 EFLAGS: 00010246 > RAX: 0021 RBX: 8807fc5afcb0 RCX: > RDX: RSI: 88081efee5f8 RDI: 88081efee5f8 > RBP: 8807fc5afc98 R08: 0096 R09: > R10: 0711 R11: 8807fc5af93e R12: a0424070 > R13: 0019 R14: a0423068 R15: 0009 > FS: 7f2d4b034740() GS:88081efe() knlGS: > CS: 0010 DS: ES: CR0: 80050033 > CR2: 7f2d4a99f3c0 CR3: 0007fd88b000 CR4: 001407e0 > Stack: > 8807fc5afcb8 8199f020 88080e396160 > a0423040 a0425000 8807fc5afd08 81076be5 > 0008 a0424053 88070018 8807fc5afd18 > Call Trace: > [] ? dummy_greetings+0x40/0x40 [dummy_module] > [] warn_slowpath_fmt+0x55/0x70 > [] init_dummy+0x28/0x30 [dummy_module] > [] do_one_initcall+0xd4/0x210 > [] ? __vunmap+0xc2/0x110 > [] load_module+0x16a9/0x1b30 > [] ? store_uevent+0x70/0x70 > [] ? copy_module_from_fd.isra.44+0x129/0x180 > [] SyS_finit_module+0xa6/0xd0 > [] system_call_fastpath+0x12/0x17 > Code: c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 48 c7 c7 20 42 8a 81 31 c0 e8 fc > 80 5e 00 eb 80 48 c7 c7 78 42 8a 81 31 c0 e8 ec 80 5e 00 <0f> 0b 66 66 66 66 > 2e > 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 > RIP [] warn_slowpath_common+0xc1/0xd0 > RSP > ---[ end trace 428218934a12088b ]--- > > Successfully tested by me. > > Cc: Jonathan Corbet > Cc: Andrew Morton > Cc: Rusty Russell > Cc: "H. Peter Anvin" > Cc: Andi Kleen > Cc: Masami Hiramatsu > Cc: Fabian Frederick > Cc: vgo...@redhat.com > Cc: isimatu.yasu...@jp.fujitsu.com > Cc: linux-...@vger.kernel.org > Cc: ke...@lists.infradead.org > Cc: linux-...@vger.kernel.org > Signed-off-by: Prarit Bhargava > > [v2]: add /proc/sys/kernel/bug_on_warn, additional documentation, modify > !slowpath cases > --- > Documentation/kdump/kdump.txt |7 +++ > Documentation/kernel-parameters.txt |3 +++ > Documentation/sysctl/kernel.txt | 12 > include/asm-generic/bug.h | 12 ++-- > include/linux/kernel.h |1 + > include/uapi/linux/sysctl.h |1 + > kernel/panic.c | 21 - > kernel/sysctl.c |7 +++ > kernel/sysctl_binary.c |1 + > 9 files changed, 62 insertions(+), 3 deletions(-) > > diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt > index 6c0b9f2..a04ed72 100644 > --- a/Documentation/kdump/kdump.txt > +++ b/Documentation/kdump/kdump.txt > @@ -471,6 +471,13 @@ format. Crash is available on Dave Anders
