From 3485b88390b0af9e05dc2c3f57e9936f41e159a0 Mon Sep 17 00:00:00 2001 From: Ryan Roberts Date: Thu, 7 Dec 2023 16:12:04 +0000 Subject: mm: thp: introduce multi-size THP sysfs interface In preparation for adding support for anonymous multi-size THP, introduce new sysfs structure that will be used to control the new behaviours. A new directory is added under transparent_hugepage for each supported THP size, and contains an `enabled` file, which can be set to "inherit" (to inherit the global setting), "always", "madvise" or "never". For now, the kernel still only supports PMD-sized anonymous THP, so only 1 directory is populated. The first half of the change converts transhuge_vma_suitable() and hugepage_vma_check() so that they take a bitfield of orders for which the user wants to determine support, and the functions filter out all the orders that can't be supported, given the current sysfs configuration and the VMA dimensions. The resulting functions are renamed to thp_vma_suitable_orders() and thp_vma_allowable_orders() respectively. Convenience functions that take a single, unencoded order and return a boolean are also defined as thp_vma_suitable_order() and thp_vma_allowable_order(). The second half of the change implements the new sysfs interface. It has been done so that each supported THP size has a `struct thpsize`, which describes the relevant metadata and is itself a kobject. This is pretty minimal for now, but should make it easy to add new per-thpsize files to the interface if needed in future (e.g. per-size defrag). Rather than keep the `enabled` state directly in the struct thpsize, I've elected to directly encode it into huge_anon_orders_[always|madvise|inherit] bitfields since this reduces the amount of work required in thp_vma_allowable_orders() which is called for every page fault. See Documentation/admin-guide/mm/transhuge.rst, as modified by this commit, for details of how the new sysfs interface works. [ryan.roberts@arm.com: fix build warning when CONFIG_SYSFS is disabled] Link: https://lkml.kernel.org/r/20231211125320.3997543-1-ryan.roberts@arm.com Link: https://lkml.kernel.org/r/20231207161211.2374093-4-ryan.roberts@arm.com Signed-off-by: Ryan Roberts Reviewed-by: Barry Song Tested-by: Kefeng Wang Tested-by: John Hubbard Acked-by: David Hildenbrand Cc: Alistair Popple Cc: Anshuman Khandual Cc: Catalin Marinas Cc: David Rientjes Cc: "Huang, Ying" Cc: Hugh Dickins Cc: Itaru Kitayama Cc: Kirill A. Shutemov Cc: Luis Chamberlain Cc: Matthew Wilcox (Oracle) Cc: Vlastimil Babka Cc: Yang Shi Cc: Yin Fengwei Cc: Yu Zhao Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/khugepaged.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) (limited to 'mm/khugepaged.c') diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 064654717843..d72aecd3624a 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -446,7 +446,8 @@ void khugepaged_enter_vma(struct vm_area_struct *vma, { if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) && hugepage_flags_enabled()) { - if (hugepage_vma_check(vma, vm_flags, false, false, true)) + if (thp_vma_allowable_order(vma, vm_flags, false, false, true, + PMD_ORDER)) __khugepaged_enter(vma->vm_mm); } } @@ -922,16 +923,16 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, if (!vma) return SCAN_VMA_NULL; - if (!transhuge_vma_suitable(vma, address)) + if (!thp_vma_suitable_order(vma, address, PMD_ORDER)) return SCAN_ADDRESS_RANGE; - if (!hugepage_vma_check(vma, vma->vm_flags, false, false, - cc->is_khugepaged)) + if (!thp_vma_allowable_order(vma, vma->vm_flags, false, false, + cc->is_khugepaged, PMD_ORDER)) return SCAN_VMA_CHECK; /* * Anon VMA expected, the address may be unmapped then * remapped to file after khugepaged reaquired the mmap_lock. * - * hugepage_vma_check may return true for qualified file + * thp_vma_allowable_order may return true for qualified file * vmas. */ if (expect_anon && (!(*vmap)->anon_vma || !vma_is_anonymous(*vmap))) @@ -1503,7 +1504,8 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, * and map it by a PMD, regardless of sysfs THP settings. As such, let's * analogously elide sysfs THP settings here. */ - if (!hugepage_vma_check(vma, vma->vm_flags, false, false, false)) + if (!thp_vma_allowable_order(vma, vma->vm_flags, false, false, false, + PMD_ORDER)) return SCAN_VMA_CHECK; /* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */ @@ -2368,7 +2370,8 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result, progress++; break; } - if (!hugepage_vma_check(vma, vma->vm_flags, false, false, true)) { + if (!thp_vma_allowable_order(vma, vma->vm_flags, false, false, + true, PMD_ORDER)) { skip: progress++; continue; @@ -2705,7 +2708,8 @@ int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev, *prev = vma; - if (!hugepage_vma_check(vma, vma->vm_flags, false, false, false)) + if (!thp_vma_allowable_order(vma, vma->vm_flags, false, false, false, + PMD_ORDER)) return -EINVAL; cc = kmalloc(sizeof(*cc), GFP_KERNEL); -- cgit v1.2.3