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Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Alexander Viro , Christian Brauner , Jan Kara , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" , Minchan Kim , Sergey Senozhatsky , Brendan Jackman , Johannes Weiner , Jason Gunthorpe , John Hubbard , Peter Xu , Xu Xin , Chengming Zhou , Miaohe Lin , Naoya Horiguchi , Oscar Salvador , Rik van Riel , Harry Yoo , Qi Zheng , Shakeel Butt References: <20250630130011.330477-1-david@redhat.com> <20250630130011.330477-14-david@redhat.com> <65804db3-71c0-47ff-8189-6a1587d4a0cc@lucifer.local> 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: <65804db3-71c0-47ff-8189-6a1587d4a0cc@lucifer.local> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: Db0_SKBfN9A7ayJN_IwUTxphuFr32nGtiINf7yXzpbc_1751365191 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: 1hd3eoehwpz5bqt4nsd6c54u84e7a7hp X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: D7D411A000C X-Rspam-User: X-HE-Tag: 1751365193-76787 X-HE-Meta: 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 y1r94LRv mCvlC5umMO5UrTvfG5TtJQQ5VNMrtfk2HLlbS752zvfBm6Yn853R+H0ztjmCxnFfaqj6XN5OynunBwvlbpv0MuaAy8LLZC3ev/kX8AWe2+sILhh5DygIxGWGpD5e4pBnOprpjv2Mto5pI4QBh+uvzxC7ohtxDkJM/6IegeRSbnC+gud/gM3ITIq/gaEGGmGG62c5I80AbuUpXgS63bWhaqFgFMw9E5tZFUY4B 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: List-Subscribe: List-Unsubscribe: On 01.07.25 12:03, Lorenzo Stoakes wrote: > On Mon, Jun 30, 2025 at 02:59:54PM +0200, David Hildenbrand wrote: >> We can just look at the balloon device (stored in page->private), to see >> if the page is still part of the balloon. >> >> As isolated balloon pages cannot get released (they are taken off the >> balloon list while isolated), we don't have to worry about this case in >> the putback and migration callback. Add a WARN_ON_ONCE for now. >> >> Signed-off-by: David Hildenbrand > > Seems reasonable, one comment below re: comment. > > Reviewed-by: Lorenzo Stoakes > >> --- >> include/linux/balloon_compaction.h | 4 +--- >> mm/balloon_compaction.c | 11 +++++++++++ >> 2 files changed, 12 insertions(+), 3 deletions(-) >> >> diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h >> index bfc6e50bd004b..9bce8e9f5018c 100644 >> --- a/include/linux/balloon_compaction.h >> +++ b/include/linux/balloon_compaction.h >> @@ -136,10 +136,8 @@ static inline gfp_t balloon_mapping_gfp_mask(void) >> */ >> static inline void balloon_page_finalize(struct page *page) >> { >> - if (IS_ENABLED(CONFIG_BALLOON_COMPACTION)) { >> - __ClearPageMovable(page); >> + if (IS_ENABLED(CONFIG_BALLOON_COMPACTION)) >> set_page_private(page, 0); >> - } >> /* PageOffline is sticky until the page is freed to the buddy. */ >> } >> >> diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c >> index ec176bdb8a78b..e4f1a122d786b 100644 >> --- a/mm/balloon_compaction.c >> +++ b/mm/balloon_compaction.c >> @@ -206,6 +206,9 @@ static bool balloon_page_isolate(struct page *page, isolate_mode_t mode) >> struct balloon_dev_info *b_dev_info = balloon_page_device(page); >> unsigned long flags; >> >> + if (!b_dev_info) >> + return false; >> + >> spin_lock_irqsave(&b_dev_info->pages_lock, flags); >> list_del(&page->lru); >> b_dev_info->isolated_pages++; >> @@ -219,6 +222,10 @@ static void balloon_page_putback(struct page *page) >> struct balloon_dev_info *b_dev_info = balloon_page_device(page); >> unsigned long flags; >> >> + /* Isolated balloon pages cannot get deflated. */ >> + if (WARN_ON_ONCE(!b_dev_info)) >> + return; >> + >> spin_lock_irqsave(&b_dev_info->pages_lock, flags); >> list_add(&page->lru, &b_dev_info->pages); >> b_dev_info->isolated_pages--; >> @@ -234,6 +241,10 @@ static int balloon_page_migrate(struct page *newpage, struct page *page, >> VM_BUG_ON_PAGE(!PageLocked(page), page); >> VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); >> >> + /* Isolated balloon pages cannot get deflated. */ > > Hm do you mean migrated? Well, they can get migrated, obviously :) Deflation would be the other code path where we would remove a balloon page from the balloon, and invalidate page->private, suddenly seeing !b_dev_info here. But that cannot happen, as isolation takes them off the balloon list. So deflating the balloon cannot find them until un-isolated. -- Cheers, David / dhildenb