This commit is co-opting the same madvise mode that is being introduced by zokeefe@xxxxxxxxxx to manually collapse THPs[1]. As with the rest of the high-granularity mapping support, MADV_COLLAPSE is only supported for shared VMAs right now. [1] https://lore.kernel.org/linux-mm/20220604004004.954674-10-zokeefe@xxxxxxxxxx/ Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx> --- include/uapi/asm-generic/mman-common.h | 2 ++ mm/madvise.c | 23 +++++++++++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h index 6c1aa92a92e4..b686920ca731 100644 --- a/include/uapi/asm-generic/mman-common.h +++ b/include/uapi/asm-generic/mman-common.h @@ -77,6 +77,8 @@ #define MADV_DONTNEED_LOCKED 24 /* like DONTNEED, but drop locked pages too */ +#define MADV_COLLAPSE 25 /* collapse an address range into hugepages */ + /* compatibility flags */ #define MAP_FILE 0 diff --git a/mm/madvise.c b/mm/madvise.c index d7b4f2602949..c624c0f02276 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -59,6 +59,7 @@ static int madvise_need_mmap_write(int behavior) case MADV_FREE: case MADV_POPULATE_READ: case MADV_POPULATE_WRITE: + case MADV_COLLAPSE: return 0; default: /* be safe, default to 1. list exceptions explicitly */ @@ -981,6 +982,20 @@ static long madvise_remove(struct vm_area_struct *vma, return error; } +static int madvise_collapse(struct vm_area_struct *vma, + struct vm_area_struct **prev, + unsigned long start, unsigned long end) +{ + bool shared = vma->vm_flags & VM_SHARED; + *prev = vma; + + /* Only allow collapsing for HGM-enabled, shared mappings. */ + if (!is_vm_hugetlb_page(vma) || !hugetlb_hgm_enabled(vma) || !shared) + return -EINVAL; + + return hugetlb_collapse(vma->vm_mm, vma, start, end); +} + /* * Apply an madvise behavior to a region of a vma. madvise_update_vma * will handle splitting a vm area into separate areas, each area with its own @@ -1011,6 +1026,8 @@ static int madvise_vma_behavior(struct vm_area_struct *vma, case MADV_POPULATE_READ: case MADV_POPULATE_WRITE: return madvise_populate(vma, prev, start, end, behavior); + case MADV_COLLAPSE: + return madvise_collapse(vma, prev, start, end); case MADV_NORMAL: new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ; break; @@ -1158,6 +1175,9 @@ madvise_behavior_valid(int behavior) #ifdef CONFIG_MEMORY_FAILURE case MADV_SOFT_OFFLINE: case MADV_HWPOISON: +#endif +#ifdef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING + case MADV_COLLAPSE: #endif return true; @@ -1351,6 +1371,9 @@ int madvise_set_anon_name(struct mm_struct *mm, unsigned long start, * triggering read faults if required * MADV_POPULATE_WRITE - populate (prefault) page tables writable by * triggering write faults if required + * MADV_COLLAPSE - collapse a high-granularity HugeTLB mapping into huge + * mappings. This is useful after an entire hugepage has been + * mapped with individual small UFFDIO_CONTINUE operations. * * return values: * zero - success -- 2.37.0.rc0.161.g10f37bed90-goog
