+ filemap-fix-the-conditional-folio_put-in-filemap_fault.patch added to mm-hotfixes-unstable branch

+ filemap-fix-the-conditional-folio_put-in-filemap_fault.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: filemap: fix the conditional folio_put in filemap_fault
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     filemap-fix-the-conditional-folio_put-in-filemap_fault.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/filemap-fix-the-conditional-folio_put-in-filemap_fault.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Christoph Hellwig <hch@lst.de>
Subject: filemap: fix the conditional folio_put in filemap_fault
Date: Wed, 3 May 2023 17:45:25 +0200

folio can't be NULL here now that __filemap_get_folio returns an ERR_PTR. 
Remove the conditional folio_put after the out_retry label and add a new
label for the cases where we have a valid folio.

Link: https://lkml.kernel.org/r/20230503154526.1223095-1-hch@lst.de
Fixes: 66dabbb65d67 ("mm: return an ERR_PTR from __filemap_get_folio")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: syzbot+48011b86c8ea329af1b9@syzkaller.appspotmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/filemap.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/mm/filemap.c~filemap-fix-the-conditional-folio_put-in-filemap_fault
+++ a/mm/filemap.c
@@ -3298,7 +3298,7 @@ retry_find:
 	}
 
 	if (!lock_folio_maybe_drop_mmap(vmf, folio, &fpin))
-		goto out_retry;
+		goto out_retry_put_folio;
 
 	/* Did it get truncated? */
 	if (unlikely(folio->mapping != mapping)) {
@@ -3334,7 +3334,7 @@ retry_find:
 	 */
 	if (fpin) {
 		folio_unlock(folio);
-		goto out_retry;
+		goto out_retry_put_folio;
 	}
 	if (mapping_locked)
 		filemap_invalidate_unlock_shared(mapping);
@@ -3363,7 +3363,7 @@ page_not_uptodate:
 	fpin = maybe_unlock_mmap_for_io(vmf, fpin);
 	error = filemap_read_folio(file, mapping->a_ops->read_folio, folio);
 	if (fpin)
-		goto out_retry;
+		goto out_retry_put_folio;
 	folio_put(folio);
 
 	if (!error || error == AOP_TRUNCATED_PAGE)
@@ -3372,14 +3372,14 @@ page_not_uptodate:
 
 	return VM_FAULT_SIGBUS;
 
+out_retry_put_folio:
+	folio_put(folio);
 out_retry:
 	/*
 	 * We dropped the mmap_lock, we need to return to the fault handler to
 	 * re-find the vma and come back and find our hopefully still populated
 	 * page.
 	 */
-	if (folio)
-		folio_put(folio);
 	if (mapping_locked)
 		filemap_invalidate_unlock_shared(mapping);
 	if (fpin)
_

Patches currently in -mm which might be from hch@lst.de are

filemap-fix-the-conditional-folio_put-in-filemap_fault.patch
afs-fix-the-afs_dir_get_folio-return-value.patch