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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672943217; bh=2xBB462x3Sc6HYYpMTo6seMnpcER1C8TouUgi6aef5c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VFcJxIx11LLNSXOAzjJz6akDEr3uhfU74pY/CnWKsOaMufTX1UHmqziwhBHoKWg79 5uPqyx38WVZNI3o1b4tKgoFhCJ5aX2YQAc8CYjgWCC+Wg2e8Zru02n6LnRj9jtDh7r y97Lwj1OZG2Jza3zxE6/UNjO25tgujX0Rxmx+ptiIQenaOMqeL1yYKJYcA+oCeLGvG l0RsxrfPLkw/FIT+IILnuhhkbVYrfLXos0p0UlZPFuHnSdl6/UlwKWc2PU9n/5V/lT PnL9bURfedZTta50PLYlRNHAKOFOUGSH2lIHpE7Y7KwHkqz6AgHXu5yafwnn7eFUsi b4b9ut/MsWW2A== Date: Thu, 5 Jan 2023 11:26:55 -0700 From: Nathan Chancellor To: Huang Ying Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zi Yan , Yang Shi , Baolin Wang , Oscar Salvador , Matthew Wilcox , Bharata B Rao , Alistair Popple , haoxin , Kees Cook Subject: Re: [PATCH 4/8] migrate_pages: split unmap_and_move() to _unmap() and _move() Message-ID: References: <20221227002859.27740-1-ying.huang@intel.com> <20221227002859.27740-5-ying.huang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221227002859.27740-5-ying.huang@intel.com> X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 7349C4000F X-Stat-Signature: 8bwgi1o1bhoac9d3b4n88ggikbkz1cew X-HE-Tag: 1672943219-327964 X-HE-Meta: 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 IwrvMUht YWSKINLdIpt8DXaH7cX2jsBPVk1vZYL4j5b+eFeEcbzJmskIqy2CcwPejWYG4A4Y9E2uNbEQiwS4RTVU9oDOYIP4F8w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Ying, On Tue, Dec 27, 2022 at 08:28:55AM +0800, Huang Ying wrote: > This is a preparation patch to batch the folio unmapping and moving. > > In this patch, unmap_and_move() is split to migrate_folio_unmap() and > migrate_folio_move(). So, we can batch _unmap() and _move() in > different loops later. To pass some information between unmap and > move, the original unused dst->mapping and dst->private are used. > > Signed-off-by: "Huang, Ying" > Cc: Zi Yan > Cc: Yang Shi > Cc: Baolin Wang > Cc: Oscar Salvador > Cc: Matthew Wilcox > Cc: Bharata B Rao > Cc: Alistair Popple > Cc: haoxin > --- > include/linux/migrate.h | 1 + > mm/migrate.c | 162 +++++++++++++++++++++++++++++----------- > 2 files changed, 121 insertions(+), 42 deletions(-) > > diff --git a/include/linux/migrate.h b/include/linux/migrate.h > index 3ef77f52a4f0..7376074f2e1e 100644 > --- a/include/linux/migrate.h > +++ b/include/linux/migrate.h > @@ -18,6 +18,7 @@ struct migration_target_control; > * - zero on page migration success; > */ > #define MIGRATEPAGE_SUCCESS 0 > +#define MIGRATEPAGE_UNMAP 1 > > /** > * struct movable_operations - Driver page migration > diff --git a/mm/migrate.c b/mm/migrate.c > index 97ea0737ab2b..e2383b430932 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1009,11 +1009,29 @@ static int move_to_new_folio(struct folio *dst, struct folio *src, > return rc; > } > > -static int __unmap_and_move(struct folio *src, struct folio *dst, > +static void __migrate_folio_record(struct folio *dst, > + unsigned long page_was_mapped, > + struct anon_vma *anon_vma) > +{ > + dst->mapping = (struct address_space *)anon_vma; > + dst->private = (void *)page_was_mapped; > +} > + > +static void __migrate_folio_extract(struct folio *dst, > + int *page_was_mappedp, > + struct anon_vma **anon_vmap) > +{ > + *anon_vmap = (struct anon_vma *)dst->mapping; > + *page_was_mappedp = (unsigned long)dst->private; > + dst->mapping = NULL; > + dst->private = NULL; > +} This patch as commit 42871c600cad ("migrate_pages: split unmap_and_move() to _unmap() and _move()") in next-20230105 causes the following error with clang when CONFIG_RANDSTRUCT is enabled, which is the case with allmodconfig: ../mm/migrate.c:1041:15: error: casting from randomized structure pointer type 'struct address_space *' to 'struct anon_vma *' *anon_vmap = (struct anon_vma *)dst->mapping; ^ 1 error generated. With GCC, there is only a note: ../mm/migrate.c: In function '__migrate_folio_extract': ../mm/migrate.c:1041:20: note: randstruct: casting between randomized structure pointer types (ssa): 'struct anon_vma' and 'struct address_space' 1041 | *anon_vmap = (struct anon_vma *)dst->mapping; | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Kees has done fixes for warnings and errors like this in the past (I just ran $ git log -p --grep='randomized structure pointer type' to find them) but I did not see any that would seem appropriate here hence just the report :) Cheers, Nathan