When processing a page fault in shared memory area for not present page, check the VMA determine if faults are to be handled by userfaultfd. If so, delegate the page fault to handle_userfault.
Signed-off-by: Mike Rapoport <[email protected]> --- mm/shmem.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 881b7a0..7ed2a1a 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -69,6 +69,7 @@ static struct vfsmount *shm_mnt; #include <linux/syscalls.h> #include <linux/fcntl.h> #include <uapi/linux/memfd.h> +#include <linux/userfaultfd_k.h> #include <linux/rmap.h> #include <asm/uaccess.h> @@ -123,13 +124,14 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp, struct shmem_inode_info *info, pgoff_t index); static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, struct page **pagep, enum sgp_type sgp, - gfp_t gfp, struct mm_struct *fault_mm, int *fault_type); + gfp_t gfp, struct vm_area_struct *vma, + struct vm_fault *vmf, int *fault_type); static inline int shmem_getpage(struct inode *inode, pgoff_t index, struct page **pagep, enum sgp_type sgp) { return shmem_getpage_gfp(inode, index, pagep, sgp, - mapping_gfp_mask(inode->i_mapping), NULL, NULL); + mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL); } static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) @@ -1129,7 +1131,7 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp, */ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, struct page **pagep, enum sgp_type sgp, gfp_t gfp, - struct mm_struct *fault_mm, int *fault_type) + struct vm_area_struct *vma, struct vm_fault *vmf, int *fault_type) { struct address_space *mapping = inode->i_mapping; struct shmem_inode_info *info; @@ -1180,7 +1182,7 @@ repeat: */ info = SHMEM_I(inode); sbinfo = SHMEM_SB(inode->i_sb); - charge_mm = fault_mm ? : current->mm; + charge_mm = vma ? vma->vm_mm : current->mm; if (swap.val) { /* Look it up and read it in.. */ @@ -1190,7 +1192,8 @@ repeat: if (fault_type) { *fault_type |= VM_FAULT_MAJOR; count_vm_event(PGMAJFAULT); - mem_cgroup_count_vm_event(fault_mm, PGMAJFAULT); + mem_cgroup_count_vm_event(vma->vm_mm, + PGMAJFAULT); } /* Here we actually start the io */ page = shmem_swapin(swap, gfp, info, index); @@ -1259,6 +1262,14 @@ repeat: swap_free(swap); } else { + if (vma && userfaultfd_missing(vma)) { + unsigned long addr = + (unsigned long)vmf->virtual_address; + *fault_type = handle_userfault(vma, addr, vmf->flags, + VM_UFFD_MISSING); + return 0; + } + if (shmem_acct_block(info->flags)) { error = -ENOSPC; goto failed; @@ -1432,7 +1443,7 @@ static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) } error = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, SGP_CACHE, - gfp, vma->vm_mm, &ret); + gfp, vma, vmf, &ret); if (error) return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); return ret; @@ -3601,7 +3612,7 @@ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, BUG_ON(mapping->a_ops != &shmem_aops); error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, - gfp, NULL, NULL); + gfp, NULL, NULL, NULL); if (error) page = ERR_PTR(error); else -- 1.9.1
