From: David Hildenbrand <david@redhat.com>
To: Sergei Trofimovich <slyfox@gentoo.org>,
Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Andrey Konovalov <andreyknvl@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v2] mm: page_alloc: ignore init_on_free=1 for debug_pagealloc=1
Date: Mon, 29 Mar 2021 11:23:23 +0200 [thread overview]
Message-ID: <e681dbc0-70b9-2185-28bf-012852f39102@redhat.com> (raw)
In-Reply-To: <20210327182144.3213887-1-slyfox@gentoo.org>
On 27.03.21 19:21, Sergei Trofimovich wrote:
> On !ARCH_SUPPORTS_DEBUG_PAGEALLOC (like ia64) debug_pagealloc=1
> implies page_poison=on:
>
> if (page_poisoning_enabled() ||
> (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
> debug_pagealloc_enabled()))
> static_branch_enable(&_page_poisoning_enabled);
>
> page_poison=on needs to init_on_free=1.
>
> Before the change id happened too late for the following case:
> - have PAGE_POISONING=y
> - have page_poison unset
> - have !ARCH_SUPPORTS_DEBUG_PAGEALLOC arch (like ia64)
> - have init_on_free=1
> - have debug_pagealloc=1
>
> That way we get both keys enabled:
> - static_branch_enable(&init_on_free);
> - static_branch_enable(&_page_poisoning_enabled);
>
> which leads to poisoned pages returned for __GFP_ZERO pages.
>
> After the change we execute only:
> - static_branch_enable(&_page_poisoning_enabled);
> and ignore init_on_free=1.
>
> CC: Vlastimil Babka <vbabka@suse.cz>
> CC: Andrew Morton <akpm@linux-foundation.org>
> CC: linux-mm@kvack.org
> CC: David Hildenbrand <david@redhat.com>
> CC: Andrey Konovalov <andreyknvl@gmail.com>
> Link: https://lkml.org/lkml/2021/3/26/443
Again, Fixes: tag? IOW, which commit initially broke it.
> Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
> ---
> mm/page_alloc.c | 30 +++++++++++++++++-------------
> 1 file changed, 17 insertions(+), 13 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index d57d9b4f7089..10a8a1d28c11 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -764,32 +764,36 @@ static inline void clear_page_guard(struct zone *zone, struct page *page,
> */
> void init_mem_debugging_and_hardening(void)
> {
> + bool page_poison_requested = page_poisoning_enabled();
s/page_poison_requested/page_poisoning_requested/
And I wonder if you should just initialize to "false" here.
Without CONFIG_PAGE_POISONING, page_poisoning_enabled() will always
return false, so it seems unnecessary.
> +
> +#ifdef CONFIG_PAGE_POISONING
> + /*
> + * Page poisoning is debug page alloc for some arches. If
> + * either of those options are enabled, enable poisoning.
> + */
> + if (page_poisoning_enabled() ||
> + (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
> + debug_pagealloc_enabled())) {
> + static_branch_enable(&_page_poisoning_enabled);
> + page_poison_requested = true;
> + }
> +#endif
Apart from that, looks good.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-03-29 9:23 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 11:26 [PATCH] mm: page_alloc: ignore init_on_free=1 for page alloc Sergei Trofimovich
2021-03-26 13:48 ` David Hildenbrand
2021-03-26 15:00 ` Andrey Konovalov
2021-03-26 16:42 ` Sergei Trofimovich
2021-03-29 12:10 ` Vlastimil Babka
2021-03-29 22:00 ` Andrey Konovalov
2021-03-29 22:07 ` Vlastimil Babka
2021-03-30 14:48 ` Andrey Konovalov
2021-03-26 14:17 ` Vlastimil Babka
2021-03-26 17:25 ` Sergei Trofimovich
2021-03-27 18:03 ` Sergei Trofimovich
2021-03-27 18:21 ` [PATCH v2] mm: page_alloc: ignore init_on_free=1 for debug_pagealloc=1 Sergei Trofimovich
2021-03-29 9:23 ` David Hildenbrand [this message]
2021-03-29 11:59 ` Vlastimil Babka
2021-03-29 22:25 ` [PATCH v3] " Sergei Trofimovich
2021-03-30 8:39 ` David Hildenbrand
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=e681dbc0-70b9-2185-28bf-012852f39102@redhat.com \
--to=david@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=andreyknvl@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=slyfox@gentoo.org \
--cc=vbabka@suse.cz \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).