From: Rik van Riel <riel@xxxxxxxxxxx> Subject: mm,thp,shmem: make khugepaged obey tmpfs mount flags Currently if thp enabled=[madvise], mounting a tmpfs filesystem with huge=always and mmapping files from that tmpfs does not result in khugepaged collapsing those mappings, despite the mount flag indicating that it should. Fix that by breaking up the blocks of tests in hugepage_vma_check a little bit, and testing things in the correct order. Link: https://lkml.kernel.org/r/20201124194925.623931-4-riel@xxxxxxxxxxx Fixes: c2231020ea7b ("mm: thp: register mm for khugepaged when merging vma for shmem") Signed-off-by: Rik van Riel <riel@xxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Xu Yu <xuyu@xxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/khugepaged.h | 2 ++ mm/khugepaged.c | 22 ++++++++++++++++------ 2 files changed, 18 insertions(+), 6 deletions(-) --- a/include/linux/khugepaged.h~mmthpshmem-make-khugepaged-obey-tmpfs-mount-flags +++ a/include/linux/khugepaged.h @@ -3,6 +3,7 @@ #define _LINUX_KHUGEPAGED_H #include <linux/sched/coredump.h> /* MMF_VM_HUGEPAGE */ +#include <linux/shmem_fs.h> #ifdef CONFIG_TRANSPARENT_HUGEPAGE @@ -57,6 +58,7 @@ static inline int khugepaged_enter(struc { if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags)) if ((khugepaged_always() || + (shmem_file(vma->vm_file) && shmem_huge_enabled(vma)) || (khugepaged_req_madv() && (vm_flags & VM_HUGEPAGE))) && !(vm_flags & VM_NOHUGEPAGE) && !test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) --- a/mm/khugepaged.c~mmthpshmem-make-khugepaged-obey-tmpfs-mount-flags +++ a/mm/khugepaged.c @@ -442,18 +442,28 @@ static inline int khugepaged_test_exit(s static bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags) { - if ((!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || - (vm_flags & VM_NOHUGEPAGE) || + /* Explicitly disabled through madvise. */ + if ((vm_flags & VM_NOHUGEPAGE) || test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) return false; - if (shmem_file(vma->vm_file) || - (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && - vma->vm_file && - (vm_flags & VM_DENYWRITE))) { + /* Enabled via shmem mount options or sysfs settings. */ + if (shmem_file(vma->vm_file) && shmem_huge_enabled(vma)) { return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, HPAGE_PMD_NR); } + + /* THP settings require madvise. */ + if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) + return false; + + /* Read-only file mappings need to be aligned for THP to work. */ + if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && vma->vm_file && + (vm_flags & VM_DENYWRITE)) { + return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, + HPAGE_PMD_NR); + } + if (!vma->anon_vma || vma->vm_ops) return false; if (vma_is_temporary_stack(vma)) _
