Revert "mm: don't allow huge faults for files with pre content watches"

This reverts commit 20bf82a.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250312073852.2123409-6-amir73il@gmail.com

mm/memory.c

@@ -76,7 +76,6 @@
 #include <linux/ptrace.h>
 #include <linux/vmalloc.h>
 #include <linux/sched/sysctl.h>
-#include <linux/fsnotify.h>
 
 #include <trace/events/kmem.h>
 
@@ -5750,17 +5749,8 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
 static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
-
 	if (vma_is_anonymous(vma))
 		return do_huge_pmd_anonymous_page(vmf);
-	/*
-	 * Currently we just emit PAGE_SIZE for our fault events, so don't allow
-	 * a huge fault if we have a pre content watch on this file.  This would
-	 * be trivial to support, but there would need to be tests to ensure
-	 * this works properly and those don't exist currently.
-	 */
-	if (unlikely(FMODE_FSNOTIFY_HSM(vma->vm_file->f_mode)))
-		return VM_FAULT_FALLBACK;
 	if (vma->vm_ops->huge_fault)
 		return vma->vm_ops->huge_fault(vmf, PMD_ORDER);
 	return VM_FAULT_FALLBACK;
@@ -5784,9 +5774,6 @@ static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf)
 	}
 
 	if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
-		/* See comment in create_huge_pmd. */
-		if (unlikely(FMODE_FSNOTIFY_HSM(vma->vm_file->f_mode)))
-			goto split;
 		if (vma->vm_ops->huge_fault) {
 			ret = vma->vm_ops->huge_fault(vmf, PMD_ORDER);
 			if (!(ret & VM_FAULT_FALLBACK))
@@ -5809,9 +5796,6 @@ static vm_fault_t create_huge_pud(struct vm_fault *vmf)
 	/* No support for anonymous transparent PUD pages yet */
 	if (vma_is_anonymous(vma))
 		return VM_FAULT_FALLBACK;
-	/* See comment in create_huge_pmd. */
-	if (unlikely(FMODE_FSNOTIFY_HSM(vma->vm_file->f_mode)))
-		return VM_FAULT_FALLBACK;
 	if (vma->vm_ops->huge_fault)
 		return vma->vm_ops->huge_fault(vmf, PUD_ORDER);
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
@@ -5829,9 +5813,6 @@ static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
 	if (vma_is_anonymous(vma))
 		goto split;
 	if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
-		/* See comment in create_huge_pmd. */
-		if (unlikely(FMODE_FSNOTIFY_HSM(vma->vm_file->f_mode)))
-			goto split;
 		if (vma->vm_ops->huge_fault) {
 			ret = vma->vm_ops->huge_fault(vmf, PUD_ORDER);
 			if (!(ret & VM_FAULT_FALLBACK))