[RFC] kernel/panic: Repeat the line and caller information at the end of the OOPS

[RFC] kernel/panic: Repeat the line and caller information at the end of the OOPS

[Chris Wilson]

For large oops dump, for example if ftrace is included, we can easily
exceed the storage buffer and lose the most important bit of
information: where the OOPS occurred. So repeat the location information
just before the end marker.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Marta Lofstedt <marta.lofstedt@intel.com>
---
 kernel/panic.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/kernel/panic.c b/kernel/panic.c
index 2cfef408fec9..51914dcd1ab8 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -517,14 +517,9 @@ struct warn_args {
 	va_list args;
 };
 
-void __warn(const char *file, int line, void *caller, unsigned taint,
-	    struct pt_regs *regs, struct warn_args *args)
+static void print_location(const char *file, int line, void *caller,
+			   struct warn_args *args)
 {
-	disable_trace_on_warning();
-
-	if (args)
-		pr_warn(CUT_HERE);
-
 	if (file)
 		pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
 			raw_smp_processor_id(), current->pid, file, line,
@@ -535,6 +530,17 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 
 	if (args)
 		vprintk(args->fmt, args->args);
+}
+
+void __warn(const char *file, int line, void *caller, unsigned taint,
+	    struct pt_regs *regs, struct warn_args *args)
+{
+	disable_trace_on_warning();
+
+	if (args)
+		pr_warn(CUT_HERE);
+
+	show_location(file, line, caller, args);
 
 	if (panic_on_warn) {
 		/*
@@ -554,6 +560,8 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 	else
 		dump_stack();
 
+	show_location(file, line, caller, args);
+
 	print_oops_end_marker();
 
 	/* Just a warning, don't kill lockdep. */
-- 
2.16.2

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Re: [RFC] kernel/panic: Repeat the line and caller information at the end of the OOPS

[Lofstedt, Marta]

Seems like a good idea to me.

+Mika

> -----Original Message-----
> From: Chris Wilson [mailto:chris@chris-wilson.co.uk]
> Sent: Monday, February 26, 2018 3:53 PM
> To: intel-gfx@lists.freedesktop.org
> Cc: Chris Wilson <chris@chris-wilson.co.uk>; Lofstedt, Marta
> <marta.lofstedt@intel.com>
> Subject: [RFC] kernel/panic: Repeat the line and caller information at the end
> of the OOPS
> 
> For large oops dump, for example if ftrace is included, we can easily exceed
> the storage buffer and lose the most important bit of
> information: where the OOPS occurred. So repeat the location information
> just before the end marker.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Marta Lofstedt <marta.lofstedt@intel.com>
> ---
>  kernel/panic.c | 22 +++++++++++++++-------
>  1 file changed, 15 insertions(+), 7 deletions(-)
> 
> diff --git a/kernel/panic.c b/kernel/panic.c index 2cfef408fec9..51914dcd1ab8
> 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -517,14 +517,9 @@ struct warn_args {
>  	va_list args;
>  };
> 
> -void __warn(const char *file, int line, void *caller, unsigned taint,
> -	    struct pt_regs *regs, struct warn_args *args)
> +static void print_location(const char *file, int line, void *caller,
> +			   struct warn_args *args)
>  {
> -	disable_trace_on_warning();
> -
> -	if (args)
> -		pr_warn(CUT_HERE);
> -
>  	if (file)
>  		pr_warn("WARNING: CPU: %d PID: %d at %s:%d
> %pS\n",
>  			raw_smp_processor_id(),
> current->pid, file, line, @@ -535,6 +530,17 @@ void __warn(const char *file,
> int line, void *caller, unsigned taint,
> 
>  	if (args)
>  		vprintk(args->fmt, args->args);
> +}
> +
> +void __warn(const char *file, int line, void *caller, unsigned taint,
> +	    struct pt_regs *regs, struct warn_args *args) {
> +	disable_trace_on_warning();
> +
> +	if (args)
> +		pr_warn(CUT_HERE);
> +
> +	show_location(file, line, caller, args);
> 
>  	if (panic_on_warn) {
>  		/*
> @@ -554,6 +560,8 @@ void __warn(const char *file, int line, void *caller,
> unsigned taint,
>  	else
>  		dump_stack();
> 
> +	show_location(file, line, caller, args);
> +
>  	print_oops_end_marker();
> 
>  	/* Just a warning, don't kill lockdep. */
> --
> 2.16.2

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✗ Fi.CI.BAT: failure for kernel/panic: Repeat the line and caller information at the end of the OOPS

[Patchwork]

== Series Details ==

Series: kernel/panic: Repeat the line and caller information at the end of the OOPS
URL   : https://patchwork.freedesktop.org/series/38962/
State : failure

== Summary ==

CHK     include/config/kernel.release
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
  CHK     include/generated/bounds.h
  CHK     include/generated/timeconst.h
  CHK     include/generated/asm-offsets.h
  CALL    scripts/checksyscalls.sh
  DESCEND  objtool
  CHK     scripts/mod/devicetable-offsets.h
  CHK     include/generated/compile.h
  CC      kernel/panic.o
kernel/panic.c: In function ‘__warn’:
kernel/panic.c:543:2: error: implicit declaration of function ‘show_location’ [-Werror=implicit-function-declaration]
  show_location(file, line, caller, args);
  ^~~~~~~~~~~~~
At top level:
kernel/panic.c:520:13: warning: ‘print_location’ defined but not used [-Wunused-function]
 static void print_location(const char *file, int line, void *caller,
             ^~~~~~~~~~~~~~
cc1: some warnings being treated as errors
scripts/Makefile.build:316: recipe for target 'kernel/panic.o' failed
make[1]: *** [kernel/panic.o] Error 1
Makefile:1048: recipe for target 'kernel' failed
make: *** [kernel] Error 2

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[RFC] kernel/panic: Repeat the line and caller information at the end of the OOPS

[Chris Wilson]

For large oops dump, for example if ftrace is included, we can easily
exceed the storage buffer and lose the most important bit of
information: where the OOPS occurred. So repeat the location information
just before the end marker.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Marta Lofstedt <marta.lofstedt@intel.com>
---
git add ftw
-Chris
---
 kernel/panic.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/kernel/panic.c b/kernel/panic.c
index 2cfef408fec9..9049168d9445 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -517,14 +517,9 @@ struct warn_args {
 	va_list args;
 };
 
-void __warn(const char *file, int line, void *caller, unsigned taint,
-	    struct pt_regs *regs, struct warn_args *args)
+static void show_location(const char *file, int line, void *caller,
+			  struct warn_args *args)
 {
-	disable_trace_on_warning();
-
-	if (args)
-		pr_warn(CUT_HERE);
-
 	if (file)
 		pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
 			raw_smp_processor_id(), current->pid, file, line,
@@ -535,6 +530,17 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 
 	if (args)
 		vprintk(args->fmt, args->args);
+}
+
+void __warn(const char *file, int line, void *caller, unsigned taint,
+	    struct pt_regs *regs, struct warn_args *args)
+{
+	disable_trace_on_warning();
+
+	if (args)
+		pr_warn(CUT_HERE);
+
+	show_location(file, line, caller, args);
 
 	if (panic_on_warn) {
 		/*
@@ -554,6 +560,8 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 	else
 		dump_stack();
 
+	show_location(file, line, caller, args);
+
 	print_oops_end_marker();
 
 	/* Just a warning, don't kill lockdep. */
-- 
2.16.2

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✓ Fi.CI.BAT: success for kernel/panic: Repeat the line and caller information at the end of the OOPS (rev2)

[Patchwork]

== Series Details ==

Series: kernel/panic: Repeat the line and caller information at the end of the OOPS (rev2)
URL   : https://patchwork.freedesktop.org/series/38962/
State : success

== Summary ==

Series 38962v2 kernel/panic: Repeat the line and caller information at the end of the OOPS
https://patchwork.freedesktop.org/api/1.0/series/38962/revisions/2/mbox/

---- Known issues:

Test debugfs_test:
        Subgroup read_all_entries:
                incomplete -> PASS       (fi-snb-2520m) fdo#103713

fdo#103713 https://bugs.freedesktop.org/show_bug.cgi?id=103713

fi-bdw-5557u     total:288  pass:267  dwarn:0   dfail:0   fail:0   skip:21  time:419s
fi-bdw-gvtdvm    total:288  pass:264  dwarn:0   dfail:0   fail:0   skip:24  time:425s
fi-blb-e6850     total:288  pass:223  dwarn:1   dfail:0   fail:0   skip:64  time:374s
fi-bsw-n3050     total:288  pass:242  dwarn:0   dfail:0   fail:0   skip:46  time:482s
fi-bwr-2160      total:288  pass:183  dwarn:0   dfail:0   fail:0   skip:105 time:283s
fi-bxt-dsi       total:288  pass:258  dwarn:0   dfail:0   fail:0   skip:30  time:477s
fi-bxt-j4205     total:288  pass:259  dwarn:0   dfail:0   fail:0   skip:29  time:479s
fi-byt-j1900     total:288  pass:253  dwarn:0   dfail:0   fail:0   skip:35  time:463s
fi-byt-n2820     total:288  pass:249  dwarn:0   dfail:0   fail:0   skip:39  time:453s
fi-cfl-8700k     total:288  pass:260  dwarn:0   dfail:0   fail:0   skip:28  time:392s
fi-cfl-s2        total:288  pass:262  dwarn:0   dfail:0   fail:0   skip:26  time:568s
fi-elk-e7500     total:288  pass:229  dwarn:0   dfail:0   fail:0   skip:59  time:408s
fi-gdg-551       total:288  pass:179  dwarn:0   dfail:0   fail:1   skip:108 time:282s
fi-glk-1         total:288  pass:260  dwarn:0   dfail:0   fail:0   skip:28  time:505s
fi-hsw-4770      total:288  pass:261  dwarn:0   dfail:0   fail:0   skip:27  time:385s
fi-ilk-650       total:288  pass:228  dwarn:0   dfail:0   fail:0   skip:60  time:408s
fi-ivb-3520m     total:288  pass:259  dwarn:0   dfail:0   fail:0   skip:29  time:452s
fi-kbl-7500u     total:288  pass:263  dwarn:1   dfail:0   fail:0   skip:24  time:452s
fi-kbl-7560u     total:288  pass:269  dwarn:0   dfail:0   fail:0   skip:19  time:485s
fi-kbl-7567u     total:288  pass:268  dwarn:0   dfail:0   fail:0   skip:20  time:449s
fi-kbl-r         total:288  pass:261  dwarn:0   dfail:0   fail:0   skip:27  time:493s
fi-pnv-d510      total:288  pass:222  dwarn:1   dfail:0   fail:0   skip:65  time:584s
fi-skl-6260u     total:288  pass:268  dwarn:0   dfail:0   fail:0   skip:20  time:422s
fi-skl-6600u     total:288  pass:261  dwarn:0   dfail:0   fail:0   skip:27  time:502s
fi-skl-6700hq    total:288  pass:262  dwarn:0   dfail:0   fail:0   skip:26  time:515s
fi-skl-6700k2    total:288  pass:264  dwarn:0   dfail:0   fail:0   skip:24  time:488s
fi-skl-6770hq    total:288  pass:268  dwarn:0   dfail:0   fail:0   skip:20  time:473s
fi-skl-guc       total:288  pass:260  dwarn:0   dfail:0   fail:0   skip:28  time:405s
fi-skl-gvtdvm    total:288  pass:265  dwarn:0   dfail:0   fail:0   skip:23  time:432s
fi-snb-2520m     total:288  pass:248  dwarn:0   dfail:0   fail:0   skip:40  time:513s
fi-snb-2600      total:288  pass:248  dwarn:0   dfail:0   fail:0   skip:40  time:402s

23012f548f1fe658192a8e43ad5af139b726676e drm-tip: 2018y-02m-26d-10h-58m-50s UTC integration manifest
360f92f614fa kernel/panic: Repeat the line and caller information at the end of the OOPS

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_8156/issues.html
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✓ Fi.CI.IGT: success for kernel/panic: Repeat the line and caller information at the end of the OOPS (rev2)

[Patchwork]

== Series Details ==

Series: kernel/panic: Repeat the line and caller information at the end of the OOPS (rev2)
URL   : https://patchwork.freedesktop.org/series/38962/
State : success

== Summary ==

---- Possible new issues:

Test pm_rc6_residency:
        Subgroup rc6-accuracy:
                skip       -> PASS       (shard-snb)

---- Known issues:

Test kms_flip:
        Subgroup 2x-flip-vs-wf_vblank-interruptible:
                fail       -> PASS       (shard-hsw) fdo#100368 +1
        Subgroup flip-vs-panning-vs-hang:
                pass       -> DMESG-WARN (shard-snb) fdo#103821
Test perf:
        Subgroup buffer-fill:
                pass       -> FAIL       (shard-apl) fdo#103755

fdo#100368 https://bugs.freedesktop.org/show_bug.cgi?id=100368
fdo#103821 https://bugs.freedesktop.org/show_bug.cgi?id=103821
fdo#103755 https://bugs.freedesktop.org/show_bug.cgi?id=103755

shard-apl        total:3460 pass:1819 dwarn:1   dfail:0   fail:8   skip:1632 time:12115s
shard-hsw        total:3460 pass:1767 dwarn:1   dfail:0   fail:1   skip:1690 time:11779s
shard-snb        total:3460 pass:1359 dwarn:2   dfail:0   fail:1   skip:2098 time:6641s
Blacklisted hosts:
shard-kbl        total:3393 pass:1909 dwarn:1   dfail:0   fail:7   skip:1475 time:9037s

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_8156/shards.html
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Re: [RFC] kernel/panic: Repeat the line and caller information at the end of the OOPS

[Chris Wilson]

Quoting Chris Wilson (2018-02-26 14:29:56)
> For large oops dump, for example if ftrace is included, we can easily
> exceed the storage buffer and lose the most important bit of
> information: where the OOPS occurred. So repeat the location information
> just before the end marker.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Marta Lofstedt <marta.lofstedt@intel.com>

I've plonked this in topic/core-for-CI to see if it is effective in
helping us nail a few bugs.
-Chris
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Re: [RFC] kernel/panic: Repeat the line and caller information at the end of the OOPS

[Lofstedt, Marta]

OK cool I'll look out for it landing, CI_DRM_3838 or CI_DRM_3839 I guess.

> -----Original Message-----
> From: Chris Wilson [mailto:chris@chris-wilson.co.uk]
> Sent: Tuesday, February 27, 2018 12:50 PM
> To: intel-gfx@lists.freedesktop.org
> Cc: Lofstedt, Marta <marta.lofstedt@intel.com>
> Subject: Re: [RFC] kernel/panic: Repeat the line and caller information at the
> end of the OOPS
> 
> Quoting Chris Wilson (2018-02-26 14:29:56)
> > For large oops dump, for example if ftrace is included, we can easily
> > exceed the storage buffer and lose the most important bit of
> > information: where the OOPS occurred. So repeat the location
> > information just before the end marker.
> >
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Marta Lofstedt <marta.lofstedt@intel.com>
> 
> I've plonked this in topic/core-for-CI to see if it is effective in helping us nail a
> few bugs.
> -Chris
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Re: [RFC] kernel/panic: Repeat the line and caller information at the end of the OOPS

[Chris Wilson]

Quoting Lofstedt, Marta (2018-02-27 11:12:52)
> OK cool I'll look out for it landing, CI_DRM_3838 or CI_DRM_3839 I guess.

Bah, wrong path. This is only called to handle WARN() and we need the
extra information in BUG(). In fact, the information we need is in a raw
printk and not given to WARN, so we'll have to try a different tack.
-Chris
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