linux-kernel - Re: [PATCH] mm: slub: add panic_on

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Date:   Fri, 1 May 2020 14:37:51 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Rafael Aquini <aquini@...hat.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        iamjoonsoo.kim@....com, rientjes@...gle.com, penberg@...nel.org,
        cl@...ux.com
Subject: Re: [PATCH] mm: slub: add panic_on_error to the debug facilities

On Fri,  1 May 2020 17:15:40 -0400 Rafael Aquini <aquini@...hat.com> wrote:

> Sometimes it is desirable to override SLUB's debug facilities
> default behavior upon stumbling on a cache or object error
> and just stop the execution in order to grab a coredump, at
> the error-spotting time, instead of trying to fix the issue
> and report in an attempt to keep the system rolling.
> 
> This patch introduces a new debug flag SLAB_PANIC_ON_ERROR,
> along with its related SLUB-machinery, in order to extend
> current slub_debug facilites and provide the aforementioned
> behavior override.
> 

Sees reasonable.

> --- a/Documentation/vm/slub.rst
> +++ b/Documentation/vm/slub.rst
> @@ -54,6 +54,8 @@ Possible debug options are::
>  			caused higher minimum slab orders
>  	-		Switch all debugging off (useful if the kernel is
>  			configured with CONFIG_SLUB_DEBUG_ON)
> +	C		Toggle panic on error (crash) to allow for post-mortem
> +			analysis of a coredump taken at the error-spotting time

nit: "toggle" means to switch to the other state.  But what we're doing
here is to set to the "on" state.  This:

--- a/Documentation/vm/slub.rst~mm-slub-add-panic_on_error-to-the-debug-facilities-fix
+++ a/Documentation/vm/slub.rst
@@ -49,12 +49,12 @@ Possible debug options are::
 	P		Poisoning (object and padding)
 	U		User tracking (free and alloc)
 	T		Trace (please only use on single slabs)
-	A		Toggle failslab filter mark for the cache
+	A		Enable failslab filter mark for the cache
 	O		Switch debugging off for caches that would have
 			caused higher minimum slab orders
 	-		Switch all debugging off (useful if the kernel is
 			configured with CONFIG_SLUB_DEBUG_ON)
-	C		Toggle panic on error (crash) to allow for post-mortem
+	C		Enable panic on error (crash) to allow for post-mortem
 			analysis of a coredump taken at the error-spotting time
 
 F.e. in order to boot just with sanity checks and red zoning one would specify::
_