pm24.git/include/linux/rmap.h, branch rust-fixes-6.10

mm: return the address from page_mapped_in_vma()

2024-05-06T00:53:45Z

The only user of this function calls page_address_in_vma() immediately after page_mapped_in_vma() calculates it and uses it to return true/false. Return the address instead, allowing memory-failure to skip the call to page_address_in_vma(). Link: https://lkml.kernel.org/r/20240412193510.2356957-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Miaohe Lin Reviewed-by: Jane Chu Cc: Dan Williams Cc: Oscar Salvador Signed-off-by: Andrew Morton

mm: track mapcount of large folios in single value

2024-05-06T00:53:28Z

Let's track the mapcount of large folios in a single value. The mapcount of a large folio currently corresponds to the sum of the entire mapcount and all page mapcounts. This sum is what we actually want to know in folio_mapcount() and it is also sufficient for implementing folio_mapped(). With PTE-mapped THP becoming more important and more widely used, we want to avoid looping over all pages of a folio just to obtain the mapcount of large folios. The comment "In the common case, avoid the loop when no pages mapped by PTE" in folio_total_mapcount() does no longer hold for mTHP that are always mapped by PTE. Further, we are planning on using folio_mapcount() more frequently, and might even want to remove page mapcounts for large folios in some kernel configs. Therefore, allow for reading the mapcount of large folios efficiently and atomically without looping over any pages. Maintain the mapcount also for hugetlb pages for simplicity. Use the new mapcount to implement folio_mapcount() and folio_mapped(). Make page_mapped() simply call folio_mapped(). We can now get rid of folio_large_is_mapped(). _nr_pages_mapped is now only used in rmap code and for debugging purposes. Keep folio_nr_pages_mapped() around, but document that its use should be limited to rmap internals and debugging purposes. This change implies one additional atomic add/sub whenever mapping/unmapping (parts of) a large folio. As we now batch RMAP operations for PTE-mapped THP during fork(), during unmap/zap, and when PTE-remapping a PMD-mapped THP, and we adjust the large mapcount for a PTE batch only once, the added overhead in the common case is small. Only when unmapping individual pages of a large folio (e.g., during COW), the overhead might be bigger in comparison, but it's essentially one additional atomic operation. Note that before the new mapcount would overflow, already our refcount would overflow: each mapping requires a folio reference. Extend the focumentation of folio_mapcount(). Link: https://lkml.kernel.org/r/20240409192301.907377-5-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Yin Fengwei Cc: Chris Zankel Cc: Hugh Dickins Cc: John Paul Adrian Glaubitz Cc: Jonathan Corbet Cc: Matthew Wilcox (Oracle) Cc: Max Filippov Cc: Miaohe Lin Cc: Muchun Song Cc: Naoya Horiguchi Cc: Peter Xu Cc: Richard Chang Cc: Rich Felker Cc: Ryan Roberts Cc: Yang Shi Cc: Yoshinori Sato Cc: Zi Yan Signed-off-by: Andrew Morton

mm/rmap: add fast-path for small folios when adding/removing/duplicating

2024-05-06T00:53:28Z

Let's add a fast-path for small folios to all relevant rmap functions. Note that only RMAP_LEVEL_PTE applies. This is a preparation for tracking the mapcount of large folios in a single value. Link: https://lkml.kernel.org/r/20240409192301.907377-4-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Yin Fengwei Cc: Chris Zankel Cc: Hugh Dickins Cc: John Paul Adrian Glaubitz Cc: Jonathan Corbet Cc: Matthew Wilcox (Oracle) Cc: Max Filippov Cc: Miaohe Lin Cc: Muchun Song Cc: Naoya Horiguchi Cc: Peter Xu Cc: Richard Chang Cc: Rich Felker Cc: Ryan Roberts Cc: Yang Shi Cc: Yoshinori Sato Cc: Zi Yan Signed-off-by: Andrew Morton

mm/rmap: always inline anon/file rmap duplication of a single PTE

2024-05-06T00:53:28Z

As we grow the code, the compiler might make stupid decisions and unnecessarily degrade fork() performance. Let's make sure to always inline functions that operate on a single PTE so the compiler will always optimize out the loop and avoid a function call. This is a preparation for maintining a total mapcount for large folios. Link: https://lkml.kernel.org/r/20240409192301.907377-3-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Yin Fengwei Cc: Chris Zankel Cc: Hugh Dickins Cc: John Paul Adrian Glaubitz Cc: Jonathan Corbet Cc: Matthew Wilcox (Oracle) Cc: Max Filippov Cc: Miaohe Lin Cc: Muchun Song Cc: Naoya Horiguchi Cc: Peter Xu Cc: Richard Chang Cc: Rich Felker Cc: Ryan Roberts Cc: Yang Shi Cc: Yoshinori Sato Cc: Zi Yan Signed-off-by: Andrew Morton

mm/treewide: rename CONFIG_HAVE_FAST_GUP to CONFIG_HAVE_GUP_FAST

2024-04-26T03:56:41Z

Nowadays, we call it "GUP-fast", the external interface includes functions like "get_user_pages_fast()", and we renamed all internal functions to reflect that as well. Let's make the config option reflect that. Link: https://lkml.kernel.org/r/20240402125516.223131-3-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Mike Rapoport (IBM) Reviewed-by: Jason Gunthorpe Reviewed-by: John Hubbard Cc: Peter Xu Signed-off-by: Andrew Morton

mm/rmap: silence VM_WARN_ON_FOLIO() in __folio_rmap_sanity_checks()

2024-01-05T18:17:43Z

Unfortunately, vm_insert_page() and friends and up passing driver-allocated folios into folio_add_file_rmap_pte() using insert_page_into_pte_locked(). While these driver-allocated folios can be compound pages (large folios), they are not proper "rmappable" folios. In these VM_MIXEDMAP VMAs, there isn't really the concept of a reverse mapping, so long-term, we should clean that up and not call into rmap code. For the time being, document how we can end up in rmap code with large folios that are not marked rmappable. Link: https://lkml.kernel.org/r/793c5cee-d5fc-4eb1-86a2-39e05686233d@redhat.com Fixes: 68f0320824fa ("mm/rmap: convert folio_add_file_rmap_range() into folio_add_file_rmap_[pte|ptes|pmd]()") Reported-by: syzbot+50ef73537bbc393a25bb@syzkaller.appspotmail.com Closes: https://lkml.kernel.org/r/000000000000014174060e09316e@google.com Signed-off-by: David Hildenbrand Cc: Matthew Wilcox (Oracle) Cc: Ryan Roberts Cc: Yin Fengwei Signed-off-by: Andrew Morton

mm: convert page_try_share_anon_rmap() to folio_try_share_anon_rmap_[pte|pmd]()

2023-12-29T19:58:56Z

Let's convert it like we converted all the other rmap functions. Don't introduce folio_try_share_anon_rmap_ptes() for now, as we don't have a user that wants rmap batching in sight. Pretty easy to add later. All users are easy to convert -- only ksm.c doesn't use folios yet but that is left for future work -- so let's just do it in a single shot. While at it, turn the BUG_ON into a WARN_ON_ONCE. Note that page_try_share_anon_rmap() so far didn't care about pte/pmd mappings (no compound parameter). We're changing that so we can perform better sanity checks and make the code actually more readable/consistent. For example, __folio_rmap_sanity_checks() will make sure that a PMD range actually falls completely into the folio. Link: https://lkml.kernel.org/r/20231220224504.646757-39-david@redhat.com Signed-off-by: David Hildenbrand Cc: Hugh Dickins Cc: Matthew Wilcox (Oracle) Cc: Muchun Song Cc: Muchun Song Cc: Peter Xu Cc: Ryan Roberts Cc: Yin Fengwei Signed-off-by: Andrew Morton

mm/rmap: remove page_try_dup_anon_rmap()

2023-12-29T19:58:56Z

All users are gone, remove page_try_dup_anon_rmap() and any remaining traces. Link: https://lkml.kernel.org/r/20231220224504.646757-38-david@redhat.com Signed-off-by: David Hildenbrand Cc: Hugh Dickins Cc: Matthew Wilcox (Oracle) Cc: Muchun Song Cc: Muchun Song Cc: Peter Xu Cc: Ryan Roberts Cc: Yin Fengwei Signed-off-by: Andrew Morton

mm/rmap: introduce folio_try_dup_anon_rmap_[pte|ptes|pmd]()

2023-12-29T19:58:55Z

The last user of page_needs_cow_for_dma() and __page_dup_rmap() are gone, remove them. Add folio_try_dup_anon_rmap_ptes() right away, we want to perform rmap baching during fork() soon. Link: https://lkml.kernel.org/r/20231220224504.646757-35-david@redhat.com Signed-off-by: David Hildenbrand Cc: Hugh Dickins Cc: Matthew Wilcox (Oracle) Cc: Muchun Song Cc: Muchun Song Cc: Peter Xu Cc: Ryan Roberts Cc: Yin Fengwei Signed-off-by: Andrew Morton

mm/rmap: convert page_dup_file_rmap() to folio_dup_file_rmap_[pte|ptes|pmd]()

2023-12-29T19:58:55Z

Let's convert page_dup_file_rmap() like the other rmap functions. As there is only a single caller, convert that single caller right away and remove page_dup_file_rmap(). Add folio_dup_file_rmap_ptes() right away, we want to perform rmap baching during fork() soon. Link: https://lkml.kernel.org/r/20231220224504.646757-34-david@redhat.com Signed-off-by: David Hildenbrand Cc: Hugh Dickins Cc: Matthew Wilcox (Oracle) Cc: Muchun Song Cc: Muchun Song Cc: Peter Xu Cc: Ryan Roberts Cc: Yin Fengwei Signed-off-by: Andrew Morton