1 files changed, 28 insertions, 98 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 2974691fdfad2..e9404290f2c63 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -47,7 +47,6 @@
 #include <linux/splice.h>
 #include <linux/rcupdate_wait.h>
 #include <linux/sched/mm.h>
-#include <linux/fsnotify.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
 #include "internal.h"
@@ -1986,8 +1985,19 @@ no_page:
 
 		if (err == -EEXIST)
 			goto repeat;
-		if (err)
+		if (err) {
+			/*
+			 * When NOWAIT I/O fails to allocate folios this could
+			 * be due to a nonblocking memory allocation and not
+			 * because the system actually is out of memory.
+			 * Return -EAGAIN so that there caller retries in a
+			 * blocking fashion instead of propagating -ENOMEM
+			 * to the application.
+			 */
+			if ((fgp_flags & FGP_NOWAIT) && err == -ENOMEM)
+				err = -EAGAIN;
 			return ERR_PTR(err);
+		}
 		/*
 		 * filemap_add_folio locks the page, and for mmap
 		 * we expect an unlocked page.
@@ -3198,14 +3208,6 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
 	unsigned long vm_flags = vmf->vma->vm_flags;
 	unsigned int mmap_miss;
 
-	/*
-	 * If we have pre-content watches we need to disable readahead to make
-	 * sure that we don't populate our mapping with 0 filled pages that we
-	 * never emitted an event for.
-	 */
-	if (unlikely(FMODE_FSNOTIFY_HSM(file->f_mode)))
-		return fpin;
-
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	/* Use the readahead code, even if readahead is disabled */
 	if ((vm_flags & VM_HUGEPAGE) && HPAGE_PMD_ORDER <= MAX_PAGECACHE_ORDER) {
@@ -3274,10 +3276,6 @@ static struct file *do_async_mmap_readahead(struct vm_fault *vmf,
 	struct file *fpin = NULL;
 	unsigned int mmap_miss;
 
-	/* See comment in do_sync_mmap_readahead. */
-	if (unlikely(FMODE_FSNOTIFY_HSM(file->f_mode)))
-		return fpin;
-
 	/* If we don't want any read-ahead, don't bother */
 	if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages)
 		return fpin;
@@ -3337,48 +3335,6 @@ static vm_fault_t filemap_fault_recheck_pte_none(struct vm_fault *vmf)
 }
 
 /**
- * filemap_fsnotify_fault - maybe emit a pre-content event.
- * @vmf:	struct vm_fault containing details of the fault.
- *
- * If we have a pre-content watch on this file we will emit an event for this
- * range.  If we return anything the fault caller should return immediately, we
- * will return VM_FAULT_RETRY if we had to emit an event, which will trigger the
- * fault again and then the fault handler will run the second time through.
- *
- * Return: a bitwise-OR of %VM_FAULT_ codes, 0 if nothing happened.
- */
-vm_fault_t filemap_fsnotify_fault(struct vm_fault *vmf)
-{
-	struct file *fpin = NULL;
-	int mask = (vmf->flags & FAULT_FLAG_WRITE) ? MAY_WRITE : MAY_ACCESS;
-	loff_t pos = vmf->pgoff >> PAGE_SHIFT;
-	size_t count = PAGE_SIZE;
-	int err;
-
-	/*
-	 * We already did this and now we're retrying with everything locked,
-	 * don't emit the event and continue.
-	 */
-	if (vmf->flags & FAULT_FLAG_TRIED)
-		return 0;
-
-	/* No watches, we're done. */
-	if (likely(!FMODE_FSNOTIFY_HSM(vmf->vma->vm_file->f_mode)))
-		return 0;
-
-	fpin = maybe_unlock_mmap_for_io(vmf, fpin);
-	if (!fpin)
-		return VM_FAULT_SIGBUS;
-
-	err = fsnotify_file_area_perm(fpin, mask, &pos, count);
-	fput(fpin);
-	if (err)
-		return VM_FAULT_SIGBUS;
-	return VM_FAULT_RETRY;
-}
-EXPORT_SYMBOL_GPL(filemap_fsnotify_fault);
-
-/**
  * filemap_fault - read in file data for page fault handling
  * @vmf:	struct vm_fault containing details of the fault
  *
@@ -3482,37 +3438,6 @@ retry_find:
 	 */
 	if (unlikely(!folio_test_uptodate(folio))) {
 		/*
-		 * If this is a precontent file we have can now emit an event to
-		 * try and populate the folio.
-		 */
-		if (!(vmf->flags & FAULT_FLAG_TRIED) &&
-		    unlikely(FMODE_FSNOTIFY_HSM(file->f_mode))) {
-			loff_t pos = folio_pos(folio);
-			size_t count = folio_size(folio);
-
-			/* We're NOWAIT, we have to retry. */
-			if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT) {
-				folio_unlock(folio);
-				goto out_retry;
-			}
-
-			if (mapping_locked)
-				filemap_invalidate_unlock_shared(mapping);
-			mapping_locked = false;
-
-			folio_unlock(folio);
-			fpin = maybe_unlock_mmap_for_io(vmf, fpin);
-			if (!fpin)
-				goto out_retry;
-
-			error = fsnotify_file_area_perm(fpin, MAY_ACCESS, &pos,
-							count);
-			if (error)
-				ret = VM_FAULT_SIGBUS;
-			goto out_retry;
-		}
-
-		/*
 		 * If the invalidate lock is not held, the folio was in cache
 		 * and uptodate and now it is not. Strange but possible since we
 		 * didn't hold the page lock all the time. Let's drop
@@ -4169,17 +4094,6 @@ retry:
 		bytes = min(chunk - offset, bytes);
 		balance_dirty_pages_ratelimited(mapping);
 
-		/*
-		 * Bring in the user page that we will copy from _first_.
-		 * Otherwise there's a nasty deadlock on copying from the
-		 * same page as we're writing to, without it being marked
-		 * up-to-date.
-		 */
-		if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) {
-			status = -EFAULT;
-			break;
-		}
-
 		if (fatal_signal_pending(current)) {
 			status = -EINTR;
 			break;
@@ -4197,6 +4111,12 @@ retry:
 		if (mapping_writably_mapped(mapping))
 			flush_dcache_folio(folio);
 
+		/*
+		 * Faults here on mmap()s can recurse into arbitrary
+		 * filesystem code. Lots of locks are held that can
+		 * deadlock. Use an atomic copy to avoid deadlocking
+		 * in page fault handling.
+		 */
 		copied = copy_folio_from_iter_atomic(folio, offset, bytes, i);
 		flush_dcache_folio(folio);
 
@@ -4222,6 +4142,16 @@ retry:
 				bytes = copied;
 				goto retry;
 			}
+
+			/*
+			 * 'folio' is now unlocked and faults on it can be
+			 * handled. Ensure forward progress by trying to
+			 * fault it in now.
+			 */
+			if (fault_in_iov_iter_readable(i, bytes) == bytes) {
+				status = -EFAULT;
+				break;
+			}
 		} else {
 			pos += status;
 			written += status;