From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id CBA2513A; Mon, 27 Nov 2023 03:53:04 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 054652F4; Mon, 27 Nov 2023 03:53:52 -0800 (PST) Received: from raptor (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 35DB03F73F; Mon, 27 Nov 2023 03:52:59 -0800 (PST) Date: Mon, 27 Nov 2023 11:52:56 +0000 From: Alexandru Elisei To: Mike Rapoport Cc: catalin.marinas@arm.com, will@kernel.org, oliver.upton@linux.dev, maz@kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, arnd@arndb.de, akpm@linux-foundation.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, mhiramat@kernel.org, hughd@google.com, pcc@google.com, steven.price@arm.com, anshuman.khandual@arm.com, vincenzo.frascino@arm.com, david@redhat.com, eugenis@google.com, kcc@google.com, hyesoo.yu@samsung.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH RFC v2 04/27] mm: migrate/mempolicy: Add hook to modify migration target gfp Message-ID: References: <20231119165721.9849-1-alexandru.elisei@arm.com> <20231119165721.9849-5-alexandru.elisei@arm.com> <20231125100322.GH636165@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231125100322.GH636165@kernel.org> Hi Mike, I really appreciate you having a look! On Sat, Nov 25, 2023 at 12:03:22PM +0200, Mike Rapoport wrote: > On Sun, Nov 19, 2023 at 04:56:58PM +0000, Alexandru Elisei wrote: > > It might be desirable for an architecture to modify the gfp flags used to > > allocate the destination page for migration based on the page that it is > > being replaced. For example, if an architectures has metadata associated > > with a page (like arm64, when the memory tagging extension is implemented), > > it can request that the destination page similarly has storage for tags > > already allocated. > > > > No functional change. > > > > Signed-off-by: Alexandru Elisei > > --- > > include/linux/migrate.h | 4 ++++ > > mm/mempolicy.c | 2 ++ > > mm/migrate.c | 3 +++ > > 3 files changed, 9 insertions(+) > > > > diff --git a/include/linux/migrate.h b/include/linux/migrate.h > > index 2ce13e8a309b..0acef592043c 100644 > > --- a/include/linux/migrate.h > > +++ b/include/linux/migrate.h > > @@ -60,6 +60,10 @@ struct movable_operations { > > /* Defined in mm/debug.c: */ > > extern const char *migrate_reason_names[MR_TYPES]; > > > > +#ifndef arch_migration_target_gfp > > +#define arch_migration_target_gfp(src, gfp) 0 > > +#endif > > + > > #ifdef CONFIG_MIGRATION > > > > void putback_movable_pages(struct list_head *l); > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > > index 10a590ee1c89..50bc43ab50d6 100644 > > --- a/mm/mempolicy.c > > +++ b/mm/mempolicy.c > > @@ -1182,6 +1182,7 @@ static struct folio *alloc_migration_target_by_mpol(struct folio *src, > > > > h = folio_hstate(src); > > gfp = htlb_alloc_mask(h); > > + gfp |= arch_migration_target_gfp(src, gfp); > > I think it'll be more robust to have arch_migration_target_gfp() to modify > the flags and return the new mask with added (or potentially removed) > flags. I did it this way so an arch won't be able to remove flags set by the MM code. There's a similar pattern in do_mmap() -> calc_vm_flag_bits() -> arch_calc_vm_flag_bits(). I'll change it to return the new mask if you think that's better. Thanks, Alex > > > nodemask = policy_nodemask(gfp, pol, ilx, &nid); > > return alloc_hugetlb_folio_nodemask(h, nid, nodemask, gfp); > > } > > @@ -1190,6 +1191,7 @@ static struct folio *alloc_migration_target_by_mpol(struct folio *src, > > gfp = GFP_TRANSHUGE; > > else > > gfp = GFP_HIGHUSER_MOVABLE | __GFP_RETRY_MAYFAIL | __GFP_COMP; > > + gfp |= arch_migration_target_gfp(src, gfp); > > > > page = alloc_pages_mpol(gfp, order, pol, ilx, nid); > > return page_rmappable_folio(page); > > -- > Sincerely yours, > Mike. >