From: Qian Cai <cai@lca.pw>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, Joonsoo Kim <iamjoonsoo.kim@lge.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Michal Hocko <mhocko@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Mel Gorman <mgorman@techsingularity.net>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH] mm, debug_pagealloc: don't rely on static keys too early
Date: Thu, 19 Dec 2019 08:16:59 -0500 [thread overview]
Message-ID: <83B24C03-1484-4DD6-9B42-029FF1B27287@lca.pw> (raw)
In-Reply-To: <20191219130612.23171-1-vbabka@suse.cz>
> On Dec 19, 2019, at 8:06 AM, Vlastimil Babka <vbabka@suse.cz> wrote:
>
> Commit 96a2b03f281d ("mm, debug_pagelloc: use static keys to enable debugging")
> has introduced a static key to reduce overhead when debug_pagealloc is compiled
> in but not enabled. It relied on the assumption that jump_label_init() is
> called before parse_early_param() as in start_kernel(), so when the
> "debug_pagealloc=on" option is parsed, it is safe to enable the static key.
>
> However, it turns out multiple architectures call parse_early_param() earlier
> from their setup_arch(). x86 also calls jump_label_init() even earlier, so no
> issue was found while testing the commit, but same is not true for e.g. ppc64
> and s390 where the kernel would not boot with debug_pagealloc=on as found by
> our QA.
This was daily tested on linux-next here for those arches and never saw an issue. Are you able to reproduce it on mainline or linux-next?
next prev parent reply other threads:[~2019-12-19 13:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-19 13:06 Vlastimil Babka
2019-12-19 13:16 ` Qian Cai [this message]
2019-12-19 13:34 ` Vlastimil Babka
2020-01-03 3:02 ` Andrew Morton
2020-01-06 8:37 ` Vlastimil Babka
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