From: Muchun Song <songmuchun@bytedance.com>
To: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
linux-m68k@lists.linux-m68k.org,
Anshuman Khandual <anshuman.khandual@arm.com>,
Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
william.kucharski@oracle.com,
Mike Kravetz <mike.kravetz@oracle.com>,
Vlastimil Babka <vbabka@suse.cz>,
geert@linux-m68k.org, schmitzmic@gmail.com,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Roman Gushchin <guro@fb.com>,
weixugc@google.com, Greg Thelen <gthelen@google.com>
Subject: Re: [RFC 1/8] mm: add overflow and underflow checks for page->_refcount
Date: Wed, 27 Oct 2021 15:46:42 +0800 [thread overview]
Message-ID: <CAMZfGtVS2ZRAsd9HLODoLa1vVp0XCcBOTXjsmpoWwDcdGaADvQ@mail.gmail.com> (raw)
In-Reply-To: <20211026173822.502506-2-pasha.tatashin@soleen.com>
On Wed, Oct 27, 2021 at 1:38 AM Pasha Tatashin
<pasha.tatashin@soleen.com> wrote:
>
> The problems with page->_refcount are hard to debug, because usually
> when they are detected, the damage has occurred a long time ago. Yet,
> the problems with invalid page refcount may be catastrophic and lead to
> memory corruptions.
>
> Reduce the scope of when the _refcount problems manifest themselves by
> adding checks for underflows and overflows into functions that modify
> _refcount.
>
> Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
I found some atomic_add/dec are replaced with atomic_add/dec_return,
those helpers with return value imply a full memory barrier around it, but
others without return value do not. Do you have any numbers to show
the impact? Maybe atomic_add/dec_return_relaxed can help this.
Thanks.
next prev parent reply other threads:[~2021-10-27 7:47 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-26 17:38 [RFC 0/8] Hardening page _refcount Pasha Tatashin
2021-10-26 17:38 ` [RFC 1/8] mm: add overflow and underflow checks for page->_refcount Pasha Tatashin
2021-10-26 19:48 ` Matthew Wilcox
2021-10-26 21:34 ` Pasha Tatashin
2021-10-27 1:21 ` Pasha Tatashin
2021-10-27 3:04 ` Matthew Wilcox
2021-10-27 18:22 ` Pasha Tatashin
2021-10-27 7:46 ` Muchun Song [this message]
2021-10-27 18:22 ` Pasha Tatashin
2021-10-28 4:08 ` Muchun Song
2021-10-26 17:38 ` [RFC 2/8] mm/hugetlb: remove useless set_page_count() Pasha Tatashin
2021-10-26 18:44 ` Mike Kravetz
2021-10-26 18:50 ` Pasha Tatashin
2021-10-26 21:19 ` Mike Kravetz
2021-10-26 17:38 ` [RFC 3/8] mm: Avoid using set_page_count() in set_page_recounted() Pasha Tatashin
2021-10-26 17:53 ` John Hubbard
2021-10-26 18:01 ` John Hubbard
2021-10-26 18:14 ` Pasha Tatashin
2021-10-26 18:21 ` Pasha Tatashin
2021-10-27 5:12 ` John Hubbard
2021-10-27 18:27 ` Pasha Tatashin
2021-10-28 1:20 ` John Hubbard
2021-10-28 1:35 ` John Hubbard
2021-11-01 14:30 ` Pasha Tatashin
2021-11-01 19:35 ` John Hubbard
2021-11-01 14:22 ` Pasha Tatashin
2021-11-01 19:31 ` John Hubbard
2021-11-01 19:42 ` John Hubbard
2021-10-26 17:38 ` [RFC 4/8] mm: remove set_page_count() from page_frag_alloc_align Pasha Tatashin
2021-10-26 17:38 ` [RFC 5/8] mm: avoid using set_page_count() when pages are freed into allocator Pasha Tatashin
2021-10-26 17:38 ` [RFC 6/8] mm: rename init_page_count() -> page_ref_init() Pasha Tatashin
2021-10-27 6:46 ` Geert Uytterhoeven
2021-10-26 17:38 ` [RFC 7/8] mm: remove set_page_count() Pasha Tatashin
2021-10-26 17:38 ` [RFC 8/8] mm: simplify page_ref_* functions Pasha Tatashin
2021-10-26 18:23 ` [RFC 0/8] Hardening page _refcount Matthew Wilcox
2021-10-26 18:30 ` Pasha Tatashin
2021-10-26 20:13 ` Matthew Wilcox
2021-10-26 21:24 ` Pasha Tatashin
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