From: Yosry Ahmed <yosryahmed@google.com>
To: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
Minchan Kim <minchan@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Matthew Wilcox <willy@infradead.org>,
Mike Rapoport <rppt@kernel.org>
Subject: Re: [RFC PATCH v2 00/21] mm/zsmalloc: Split zsdesc from struct page
Date: Thu, 20 Jul 2023 14:57:15 -0700 [thread overview]
Message-ID: <CAJD7tkZ=GsH_Ru2L+VnWOg8j81x_zTaGcmDxFLnEOEbBHzkehA@mail.gmail.com> (raw)
In-Reply-To: <CAB=+i9Quz9iP2-Lq=oQfKVVnzPDtOaKMm=hUPbnRg5hRxH+qaA@mail.gmail.com>
On Thu, Jul 20, 2023 at 2:52 PM Hyeonggon Yoo <42.hyeyoo@gmail.com> wrote:
>
> On Fri, Jul 21, 2023 at 6:39 AM Yosry Ahmed <yosryahmed@google.com> wrote:
> >
> > <snip>
> > >
> > > > > > It seems to me though the sizeof(zsdesc) is actually 56 bytes (on
> > > > > > 64-bit), so sizeof(zsdesc) + sizeof(memdesc) would be equal to the
> > > > > > current size of struct page. If that's true, then there is no loss,
> > > > >
> > > > > Yeah, zsdesc would be 56 bytes on 64 bit CPUs as memcg_data field is
> > > > > not used in zsmalloc.
> > > > > More fields in the current struct page might not be needed in the
> > > > > future, although it's hard to say at the moment.
> > > > > but it's not a loss.
> > > >
> > > > Is page->memcg_data something that we can drop? Aren't there code
> > > > paths that will check page->memcg_data even for kernel pages (e.g.
> > > > __folio_put() -> __folio_put_small() -> mem_cgroup_uncharge() ) ?
> > >
> > > zsmalloc pages are not accounted for via __GFP_ACCOUNT,
> >
> > Yeah, but the code in the free path above will check page->memcg_data
> > nonetheless to check if it is charged.
>
> Right.
>
> > I think to drop memcg_data we need to enlighten the code that some pages
> > do not even have memcg_data at all
>
> I agree with you. It should be one of the milestones for all of this to work.
> It won't be complicated for the code to be aware of it, because there will be
> a freeing (and uncharging if need) routine per type of descriptors.
Right.
For this patch series, do we need to maintain memcg_data in zsdec to
avoid any subtle problems?
prev parent reply other threads:[~2023-07-20 21:57 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-13 4:20 Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 01/21] mm/zsmalloc: create new struct zsdesc Hyeonggon Yoo
2023-07-20 7:47 ` Sergey Senozhatsky
2023-07-13 4:20 ` [RFC PATCH v2 02/21] mm/zsmalloc: add utility functions for zsdesc Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 03/21] mm/zsmalloc: replace first_page to first_zsdesc in struct zspage Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 04/21] mm/zsmalloc: add alternatives of frequently used helper functions Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 05/21] mm/zsmalloc: convert {try,}lock_zspage() to use zsdesc Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 06/21] mm/zsmalloc: convert __zs_{map,unmap}_object() " Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 07/21] mm/zsmalloc: convert obj_to_location() and its users " Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 08/21] mm/zsmalloc: convert obj_malloc() " Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 09/21] mm/zsmalloc: convert create_page_chain() and its user " Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 10/21] mm/zsmalloc: convert obj_allocated() and related helpers " Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 11/21] mm/zsmalloc: convert init_zspage() " Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 12/21] mm/zsmalloc: convert obj_to_page() and zs_free() " Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 13/21] mm/zsmalloc: convert reset_page() to reset_zsdesc() Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 14/21] mm/zsmalloc: convert zs_page_{isolate,migrate,putback} to use zsdesc Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 15/21] mm/zsmalloc: convert __free_zspage() " Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 16/21] mm/zsmalloc: convert location_to_obj() " Hyeonggon Yoo
2023-07-20 7:49 ` Sergey Senozhatsky
2023-07-13 4:20 ` [RFC PATCH v2 17/21] mm/zsmalloc: convert migrate_zspage() " Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 18/21] mm/zsmalloc: convert get_zspage() to take zsdesc Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 19/21] mm/zsmalloc: convert SetZsPageMovable() to use zsdesc Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 20/21] mm/zsmalloc: remove now unused helper functions Hyeonggon Yoo
2023-07-13 4:20 ` [RFC PATCH v2 21/21] mm/zsmalloc: convert {get,set}_first_obj_offset() to use zsdesc Hyeonggon Yoo
2023-07-20 7:18 ` [RFC PATCH v2 00/21] mm/zsmalloc: Split zsdesc from struct page Sergey Senozhatsky
2023-07-20 7:54 ` Yosry Ahmed
2023-07-20 11:34 ` Hyeonggon Yoo
2023-07-20 18:31 ` Yosry Ahmed
2023-07-20 21:33 ` Hyeonggon Yoo
2023-07-20 21:38 ` Yosry Ahmed
2023-07-20 21:52 ` Hyeonggon Yoo
2023-07-20 21:57 ` Yosry Ahmed [this message]
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