From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: andrey.konovalov@linux.dev
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andrey Konovalov <andreyknvl@gmail.com>,
Marco Elver <elver@google.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
Vlastimil Babka <vbabka@suse.cz>,
Matthew Wilcox <willy@infradead.org>,
linux-kernel@vger.kernel.org,
Andrey Konovalov <andreyknvl@google.com>
Subject: Re: [PATCH] mm, kasan: fix __GFP_BITS_SHIFT definition breaking LOCKDEP
Date: Mon, 28 Mar 2022 19:03:20 +0200 [thread overview]
Message-ID: <YkHqWKRRtnQuAVa/@linutronix.de> (raw)
In-Reply-To: <462ff52742a1fcc95a69778685737f723ee4dfb3.1648400273.git.andreyknvl@google.com>
On 2022-03-27 19:00:23 [+0200], andrey.konovalov@linux.dev wrote:
> From: Andrey Konovalov <andreyknvl@google.com>
>
> KASAN changes that added new GFP flags mistakenly updated __GFP_BITS_SHIFT
> as the total number of GFP bits instead of as a shift used to define
> __GFP_BITS_MASK.
>
> This broke LOCKDEP, as __GFP_BITS_MASK now gets the 25th bit enabled
> instead of the 28th for __GFP_NOLOCKDEP.
>
> Update __GFP_BITS_SHIFT to always count KASAN GFP bits.
>
> In the future, we could handle all combinations of KASAN and LOCKDEP to
> occupy as few bits as possible. For now, we have enough GFP bits to be
> inefficient in this quick fix.
>
> Fixes: 9353ffa6e9e9 ("kasan, page_alloc: allow skipping memory init for HW_TAGS")
> Fixes: 53ae233c30a6 ("kasan, page_alloc: allow skipping unpoisoning for HW_TAGS")
> Fixes: f49d9c5bb15c ("kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS")
> Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Sebastian
prev parent reply other threads:[~2022-03-28 17:03 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-27 17:00 andrey.konovalov
2022-03-28 10:09 ` Vlastimil Babka
2022-03-28 17:03 ` Sebastian Andrzej Siewior [this message]
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