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[2003:cb:c705:1400:78ba:c2d2:22a1:8858]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3608accd8b3sm7966387f8f.71.2024.06.17.23.35.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Jun 2024 23:35:28 -0700 (PDT) Message-ID: Date: Tue, 18 Jun 2024 08:35:27 +0200 Precedence: bulk X-Mailing-List: linux-debuggers@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] mm: convert page type macros to enum To: Andrew Morton , Stephen Brennan Cc: linux-mm@kvack.org, Vlastimil Babka , "Vishal Moola (Oracle)" , Omar Sandoval , "Matthew Wilcox (Oracle)" , Hao Ge , linux-debuggers@vger.kernel.org, linux-kernel@vger.kernel.org References: <20240607202954.1198180-1-stephen.s.brennan@oracle.com> <20240607212738.bf55318aebd7172fadaa11c5@linux-foundation.org> <87ikygo1yb.fsf@oracle.com> <87bk3z1f76.fsf@oracle.com> <20240617142951.08a9cdc791c8edeeca50509b@linux-foundation.org> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20240617142951.08a9cdc791c8edeeca50509b@linux-foundation.org> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 17.06.24 23:29, Andrew Morton wrote: > On Mon, 17 Jun 2024 13:34:21 -0700 Stephen Brennan wrote: > >>>>> Fixes: 46df8e73a4a3 ("mm: free up PG_slab") >>>> >>>> Should we backport this into 6.9.x? >>> >>> Hi Andrew, >>> >>> Looks like commit 46df8e73a4a3 ("mm: free up PG_slab") is introduced in >>> the v6.10-rc's, and not backported to 6.9. So PG_slab is still part of >> >> Hi Andrew, >> >> I saw that you've merged this into mm-unstable, thank you! >> >> Since 46df8e73a4a3 ("mm: free up PG_slab") is part of the current 6.10 >> RC, it would be great if this patch could be part of the 6.10 release so >> we don't release a kernel missing the PG_slab info. >> >> Can you confirm if mm-unstable will get merged in this release cycle? Or >> else, would it be possible to include it in a branch that will? > > Turns out the patch as sent was based on David's "mm: allow reuse of > the lower 16 bit of the page type with an actual type", which changed > the page flags a lot, I redid this patch thusly: > > --- a/include/linux/page-flags.h~mm-convert-page-type-macros-to-enum > +++ a/include/linux/page-flags.h > @@ -944,15 +944,22 @@ PAGEFLAG_FALSE(HasHWPoisoned, has_hwpois > * mistaken for a page type value. > */ > > -#define PAGE_TYPE_BASE 0xf0000000 > -/* Reserve 0x0000007f to catch underflows of _mapcount */ > -#define PAGE_MAPCOUNT_RESERVE -128 > -#define PG_buddy 0x00000080 > -#define PG_offline 0x00000100 > -#define PG_table 0x00000200 > -#define PG_guard 0x00000400 > -#define PG_hugetlb 0x00000800 > -#define PG_slab 0x00001000 > +enum pagetype { > + /* > + * Reserve 0xffff0000 - 0xfffffffe to catch _mapcount underflows and > + * allow owners that set a type to reuse the lower 16 bit for their own > + * purposes. > + */ As noted, we better maintain the original comment here. > + PG_buddy = 0x00000080, > + PG_offline = 0x00000100, > + PG_table = 0x00000200, > + PG_guard = 0x00000400, > + PG_hugetlb = 0x00000800, > + PG_slab = 0x00001000, > + > + PAGE_TYPE_BASE = 0xf0000000, > + PAGE_MAPCOUNT_RESERVE = -128, > +}; > > #define PageType(page, flag) \ > ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE) > _ > Apart from that LGTM. > (please check carefully) > > and David's later "mm: allow reuse of the lower 16 bit of the page type > with an actual type" becomes > > include/linux/mm_types.h | 5 +++++ > include/linux/page-flags.h | 16 ++++++++-------- > 2 files changed, 13 insertions(+), 8 deletions(-) > > --- a/include/linux/mm_types.h~mm-allow-reuse-of-the-lower-16-bit-of-the-page-type-with-an-actual-type > +++ a/include/linux/mm_types.h > @@ -157,6 +157,11 @@ struct page { > * > * See page-flags.h for a list of page types which are currently > * stored here. > + * > + * Owners of typed folios may reuse the lower 16 bit of the > + * head page page_type field after setting the page type, > + * but must reset these 16 bit to -1 before clearing the > + * page type. > */ > unsigned int page_type; > > --- a/include/linux/page-flags.h~mm-allow-reuse-of-the-lower-16-bit-of-the-page-type-with-an-actual-type > +++ a/include/linux/page-flags.h > @@ -951,15 +951,15 @@ enum pagetype { > * allow owners that set a type to reuse the lower 16 bit for their own > * purposes. > */ > - PG_buddy = 0x00000080, > - PG_offline = 0x00000100, > - PG_table = 0x00000200, > - PG_guard = 0x00000400, > - PG_hugetlb = 0x00000800, > - PG_slab = 0x00001000, > + PG_buddy = 0x40000000, > + PG_offline = 0x20000000, > + PG_table = 0x10000000, > + PG_guard = 0x08000000, > + PG_hugetlb = 0x04008000, > + PG_slab = 0x02000000, > > - PAGE_TYPE_BASE = 0xf0000000, > - PAGE_MAPCOUNT_RESERVE = -128, > + PAGE_TYPE_BASE = 0x80000000, > + PAGE_MAPCOUNT_RESERVE = (~0x0000ffff), > }; > > #define PageType(page, flag) \ > _ > > and that patch's fixup becomes > > --- a/include/linux/page-flags.h~mm-allow-reuse-of-the-lower-16-bit-of-the-page-type-with-an-actual-type-fix > +++ a/include/linux/page-flags.h > @@ -955,7 +955,7 @@ enum pagetype { > PG_offline = 0x20000000, > PG_table = 0x10000000, > PG_guard = 0x08000000, > - PG_hugetlb = 0x04008000, > + PG_hugetlb = 0x04000000, > PG_slab = 0x02000000, > > PAGE_TYPE_BASE = 0x80000000, > _ > > and "mm/zsmalloc: use a proper page type" becomes, in part, > > --- a/include/linux/page-flags.h~mm-zsmalloc-use-a-proper-page-type > +++ a/include/linux/page-flags.h > @@ -957,6 +957,7 @@ enum pagetype { > PG_guard = 0x08000000, > PG_hugetlb = 0x04000000, > PG_slab = 0x02000000, > + PG_zsmalloc = 0x01000000, > > PAGE_TYPE_BASE = 0x80000000, > PAGE_MAPCOUNT_RESERVE = (~0x0000ffff), > > > > and the end result is identical to yesterday's mm-everything so that's > all good. Looks good. > > However I wouldn't want to send the altered version of "mm: convert > page type macros to enum" into 6.10-rcX because it gets so altered by > David's mm-unstable changes for the next merge window. The new version > of the hotfixes patch won't have had any valid testing on its own. > > So I'll temporarily drop David's "mm: page_type, zsmalloc and > page_mapcount_reset()" series from mm-unstable. To permit the new "mm: > convert page type macros to enum" to get some linux-next exposure. > David, please remind me to restore that series in a week or so? I'll be on vacation next week, but will try to think of it. If you want a resend based on the new mm-unstable state with that hotfix, let me know. -- Cheers, David / dhildenb