mm: fix khugepaged with shmem_enabled=advise

Pass vm_flags as a parameter to shmem_is_huge, rather than reading the
flags from the vm_area_struct in question.  This allows the updated flags
from hugepage_madvise to be passed to the check, which is necessary
because madvise does not update the vm_area_struct's flags until after
hugepage_madvise returns.

This fixes an issue when shmem_enabled=madvise, where MADV_HUGEPAGE on
shmem was not able to register the mm_struct with khugepaged.  Prior to
cd89fb065099, the mm_struct was registered by MADV_HUGEPAGE regardless of
the value of shmem_enabled (which was only checked when scanning vmas).

Link: https://lkml.kernel.org/r/20230113023011.1784015-1-stevensd@google.com
Fixes: cd89fb065099 ("mm,thp,shmem: make khugepaged obey tmpfs mount flags")
Signed-off-by: David Stevens <stevensd@chromium.org>
Cc: David Stevens <stevensd@chromium.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 9 insertions, 9 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index c5048c6c83dd..9e1015cbad29 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -468,15 +468,14 @@ static bool shmem_confirm_swap(struct address_space *mapping,
 
 static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER;
 
-bool shmem_is_huge(struct vm_area_struct *vma, struct inode *inode,
-		   pgoff_t index, bool shmem_huge_force)
+bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
+		   struct mm_struct *mm, unsigned long vm_flags)
 {
 	loff_t i_size;
 
 	if (!S_ISREG(inode->i_mode))
 		return false;
-	if (vma && ((vma->vm_flags & VM_NOHUGEPAGE) ||
-	    test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)))
+	if (mm && ((vm_flags & VM_NOHUGEPAGE) || test_bit(MMF_DISABLE_THP, &mm->flags)))
 		return false;
 	if (shmem_huge == SHMEM_HUGE_DENY)
 		return false;
@@ -493,7 +492,7 @@ bool shmem_is_huge(struct vm_area_struct *vma, struct inode *inode,
 			return true;
 		fallthrough;
 	case SHMEM_HUGE_ADVISE:
-		if (vma && (vma->vm_flags & VM_HUGEPAGE))
+		if (mm && (vm_flags & VM_HUGEPAGE))
 			return true;
 		fallthrough;
 	default:
@@ -676,8 +675,8 @@ static long shmem_unused_huge_count(struct super_block *sb,
 
 #define shmem_huge SHMEM_HUGE_DENY
 
-bool shmem_is_huge(struct vm_area_struct *vma, struct inode *inode,
-		   pgoff_t index, bool shmem_huge_force)
+bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
+		   struct mm_struct *mm, unsigned long vm_flags)
 {
 	return false;
 }
@@ -1068,7 +1067,7 @@ static int shmem_getattr(struct user_namespace *mnt_userns,
 			STATX_ATTR_NODUMP);
 	generic_fillattr(&init_user_ns, inode, stat);
 
-	if (shmem_is_huge(NULL, inode, 0, false))
+	if (shmem_is_huge(inode, 0, false, NULL, 0))
 		stat->blksize = HPAGE_PMD_SIZE;
 
 	if (request_mask & STATX_BTIME) {
@@ -1926,7 +1925,8 @@ repeat:
 		return 0;
 	}
 
-	if (!shmem_is_huge(vma, inode, index, false))
+	if (!shmem_is_huge(inode, index, false,
+			   vma ? vma->vm_mm : NULL, vma ? vma->vm_flags : 0))
 		goto alloc_nohuge;
 
 	huge_gfp = vma_thp_gfp_mask(vma);