[...]
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 45ec3f5ef839..49f78d643392 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1341,7 +1341,17 @@ static int prepare_uptodate_page(struct inode
*inode,
unlock_page(page);
return -EIO;
}
- if (page->mapping != inode->i_mapping) {
+
+ /*
+ * Since btrfs_readpage() will get the page unlocked, we
have
+ * a window where fadvice() can try to release the page.
+ * Here we check both inode mapping and PagePrivate() to
+ * make sure the page is not released.
+ *
+ * The priavte flag check is essential for subpage as we
need
+ * to store extra bitmap using page->private.
+ */
+ if (page->mapping != inode->i_mapping ||
PagePrivate(page)) {
^ Obviously it should be !PagePrivate(page).
Hi Ritesh,
Mind to have another try on generic/095?
This time the branch is updated with the following commit at top:
commit d700b16dced6f2e2b47e1ca5588a92216ce84dfb (HEAD -> subpage,
github/subpage)
Author: Qu Wenruo <w...@suse.com>
Date: Mon Apr 19 13:41:31 2021 +0800
btrfs: fix a crash caused by race between prepare_pages() and
btrfs_releasepage()
The fix uses the PagePrivate() check to avoid the problem, and passes
several generic/auto loops without any sign of crash.
But considering I always have difficult in reproducing the bug with
previous improper fix, your verification would be very helpful.
Thanks,
Qu
Thanks,
Qu
unlock_page(page);
return -EAGAIN;
}
-ritesh
