kernel/git/stable/linux-stable.git/mm/rmap.c, branch linux-6.14.y

mm/rmap: reject hugetlb folios in folio_make_device_exclusive()

2025-04-20T08:23:08+00:00

commit bc3fe6805cf09a25a086573a17d40e525208c5d8 upstream. Even though FOLL_SPLIT_PMD on hugetlb now always fails with -EOPNOTSUPP, let's add a safety net in case FOLL_SPLIT_PMD usage would ever be reworked. In particular, before commit 9cb28da54643 ("mm/gup: handle hugetlb in the generic follow_page_mask code"), GUP(FOLL_SPLIT_PMD) would just have returned a page. In particular, hugetlb folios that are not PMD-sized would never have been prone to FOLL_SPLIT_PMD. hugetlb folios can be anonymous, and page_make_device_exclusive_one() is not really prepared for handling them at all. So let's spell that out. Link: https://lkml.kernel.org/r/20250210193801.781278-3-david@redhat.com Fixes: b756a3b5e7ea ("mm: device exclusive memory access") Signed-off-by: David Hildenbrand Reviewed-by: Alistair Popple Tested-by: Alistair Popple Cc: Alex Shi Cc: Danilo Krummrich Cc: Dave Airlie Cc: Jann Horn Cc: Jason Gunthorpe Cc: Jerome Glisse Cc: John Hubbard Cc: Jonathan Corbet Cc: Karol Herbst Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Lyude Cc: "Masami Hiramatsu (Google)" Cc: Oleg Nesterov Cc: Pasha Tatashin Cc: Peter Xu Cc: Peter Zijlstra (Intel) Cc: SeongJae Park Cc: Simona Vetter Cc: Vlastimil Babka Cc: Yanteng Si Cc: Barry Song Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm: mass constification of folio/page pointers

2024-11-07T22:38:07+00:00

Now that page_pgoff() takes const pointers, we can constify the pointers to a lot of functions. Link: https://lkml.kernel.org/r/20241005200121.3231142-5-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton

mm: renovate page_address_in_vma()

2024-11-07T22:38:07+00:00

This function doesn't modify any of its arguments, so if we make a few other functions take const pointers, we can make page_address_in_vma() take const pointers too. All of its callers have the containing folio already, so pass that in as an argument instead of recalculating it. Also add kernel-doc Link: https://lkml.kernel.org/r/20241005200121.3231142-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton

mm: use page_pgoff() in more places

2024-11-07T22:38:07+00:00

There are several places which currently open-code page_pgoff(), convert them to call it. Link: https://lkml.kernel.org/r/20241005200121.3231142-3-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton

mm: convert page_to_pgoff() to page_pgoff()

2024-11-07T22:38:07+00:00

Patch series "page->index removals in mm", v2. As part of shrinking struct page, we need to stop using page->index. This patchset gets rid of most of the remaining references to page->index in mm, as well as increasing the number of functions which take a const folio/page pointer. It shrinks the text segment of mm by a few hundred bytes in my test config, probably mostly from removing calls to compound_head() in page_to_pgoff(). This patch (of 7): Change the function signature to pass in the folio as all three callers have it. This removes a reference to page->index, which we're trying to get rid of. And add kernel-doc. Link: https://lkml.kernel.org/r/20241005200121.3231142-1-willy@infradead.org Link: https://lkml.kernel.org/r/20241005200121.3231142-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton

memcg-v1: remove memcg move locking code

2024-11-07T04:11:19+00:00

The memcg v1's charge move feature has been deprecated. All the places using the memcg move lock, have stopped using it as they don't need the protection any more. Let's proceed to remove all the locking code related to charge moving. Link: https://lkml.kernel.org/r/20241025012304.2473312-7-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt Acked-by: Michal Hocko Reviewed-by: Roman Gushchin Acked-by: Johannes Weiner Cc: Hugh Dickins Cc: Muchun Song Cc: Yosry Ahmed Signed-off-by: Andrew Morton

mm: multi-gen LRU: use {ptep,pmdp}_clear_young_notify()

2024-11-03T18:47:03+00:00

When the MM_WALK capability is enabled, memory that is mostly accessed by a VM appears younger than it really is, therefore this memory will be less likely to be evicted. Therefore, the presence of a running VM can significantly increase swap-outs for non-VM memory, regressing the performance for the rest of the system. Fix this regression by always calling {ptep,pmdp}_clear_young_notify() whenever we clear the young bits on PMDs/PTEs. [jthoughton@google.com: fix link-time error] Link: https://lkml.kernel.org/r/20241019012940.3656292-3-jthoughton@google.com Fixes: bd74fdaea146 ("mm: multi-gen LRU: support page table walks") Signed-off-by: Yu Zhao Signed-off-by: James Houghton Reported-by: David Stevens Cc: Axel Rasmussen Cc: David Matlack Cc: David Rientjes Cc: Oliver Upton Cc: Paolo Bonzini Cc: Sean Christopherson Cc: Wei Xu Cc: Cc: kernel test robot Signed-off-by: Andrew Morton

mm: introduce a pageflag for partially mapped folios

2024-09-09T23:39:04+00:00

Currently folio->_deferred_list is used to keep track of partially_mapped folios that are going to be split under memory pressure. In the next patch, all THPs that are faulted in and collapsed by khugepaged are also going to be tracked using _deferred_list. This patch introduces a pageflag to be able to distinguish between partially mapped folios and others in the deferred_list at split time in deferred_split_scan. Its needed as __folio_remove_rmap decrements _mapcount, _large_mapcount and _entire_mapcount, hence it won't be possible to distinguish between partially mapped folios and others in deferred_split_scan. Eventhough it introduces an extra flag to track if the folio is partially mapped, there is no functional change intended with this patch and the flag is not useful in this patch itself, it will become useful in the next patch when _deferred_list has non partially mapped folios. Link: https://lkml.kernel.org/r/20240830100438.3623486-5-usamaarif642@gmail.com Signed-off-by: Usama Arif Cc: Alexander Zhu Cc: Barry Song Cc: David Hildenbrand Cc: Domenico Cerasuolo Cc: Johannes Weiner Cc: Jonathan Corbet Cc: Kairui Song Cc: Matthew Wilcox Cc: Mike Rapoport Cc: Nico Pache Cc: Rik van Riel Cc: Roman Gushchin Cc: Ryan Roberts Cc: Shakeel Butt Cc: Shuang Zhai Cc: Yu Zhao Cc: Shuang Zhai Cc: Hugh Dickins Signed-off-by: Andrew Morton

mm: count the number of anonymous THPs per size

2024-09-09T23:38:57+00:00

Patch series "mm: count the number of anonymous THPs per size", v4. Knowing the number of transparent anon THPs in the system is crucial for performance analysis. It helps in understanding the ratio and distribution of THPs versus small folios throughout the system. Additionally, partial unmapping by userspace can lead to significant waste of THPs over time and increase memory reclamation pressure. We need this information for comprehensive system tuning. This patch (of 2): Let's track for each anonymous THP size, how many of them are currently allocated. We'll track the complete lifespan of an anon THP, starting when it becomes an anon THP ("large anon folio") (->mapping gets set), until it gets freed (->mapping gets cleared). Introduce a new "nr_anon" counter per THP size and adjust the corresponding counter in the following cases: * We allocate a new THP and call folio_add_new_anon_rmap() to map it the first time and turn it into an anon THP. * We split an anon THP into multiple smaller ones. * We migrate an anon THP, when we prepare the destination. * We free an anon THP back to the buddy. Note that AnonPages in /proc/meminfo currently tracks the total number of *mapped* anonymous *pages*, and therefore has slightly different semantics. In the future, we might also want to track "nr_anon_mapped" for each THP size, which might be helpful when comparing it to the number of allocated anon THPs (long-term pinning, stuck in swapcache, memory leaks, ...). Further note that for now, we only track anon THPs after they got their ->mapping set, for example via folio_add_new_anon_rmap(). If we would allocate some in the swapcache, they will only show up in the statistics for now after they have been mapped to user space the first time, where we call folio_add_new_anon_rmap(). [akpm@linux-foundation.org: documentation fixups, per David] Link: https://lkml.kernel.org/r/3e8add35-e26b-443b-8a04-1078f4bc78f6@redhat.com Link: https://lkml.kernel.org/r/20240824010441.21308-1-21cnbao@gmail.com Link: https://lkml.kernel.org/r/20240824010441.21308-2-21cnbao@gmail.com Signed-off-by: Barry Song Acked-by: David Hildenbrand Cc: Baolin Wang Cc: Chris Li Cc: Chuanhua Han Cc: Kairui Song Cc: Kalesh Singh Cc: Lance Yang Cc: Ryan Roberts Cc: Shuai Yuan Cc: Usama Arif Cc: Zi Yan Signed-off-by: Andrew Morton

mm/rmap: use folio->_mapcount for small folios

2024-09-04T04:15:37+00:00

We have some cases left whereby we operate on small folios and still refer to page->_mapcount. Let's just use folio->_mapcount instead, which currently still overlays page->_mapcount, so no change. This change will make it easier to later spot any remaining users of page->_mapcount that target tail pages. Link: https://lkml.kernel.org/r/20240816103246.719209-1-david@redhat.com Signed-off-by: David Hildenbrand Cc: Matthew Wilcox Signed-off-by: Andrew Morton