linux-kernel - [PATCH bpf-next] mm: mmap: increase sockets maximum memory size pgoff for 32bits

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Date:   Mon, 12 Aug 2019 14:34:29 +0300
From:   Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
To:     bjorn.topel@...el.com, linux-mm@...ck.org
Cc:     xdp-newbies@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, ast@...nel.org,
        magnus.karlsson@...el.com,
        Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
Subject: [PATCH bpf-next] mm: mmap: increase sockets maximum memory size pgoff for 32bits

The AF_XDP sockets umem mapping interface uses XDP_UMEM_PGOFF_FILL_RING
and XDP_UMEM_PGOFF_COMPLETION_RING offsets. The offsets seems like are
established already and are part of configuration interface.

But for 32-bit systems, while AF_XDP socket configuration, the values
are to large to pass maximum allowed file size verification.
The offsets can be tuned ofc, but instead of changing existent
interface - extend max allowed file size for sockets. The 64-bit
systems seems like ok with this, so extend threshold only for
32-bits for now.

Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
---

Based on bpf-next/master

 mm/mmap.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/mmap.c b/mm/mmap.c
index 7e8c3e8ae75f..238ce6b71405 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1358,6 +1358,11 @@ static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
 	if (S_ISBLK(inode->i_mode))
 		return MAX_LFS_FILESIZE;

+#if BITS_PER_LONG == 32
+	if (S_ISSOCK(inode->i_mode))
+		return MAX_LFS_FILESIZE;
+#endif
+
 	/* Special "we do even unsigned file positions" case */
 	if (file->f_mode & FMODE_UNSIGNED_OFFSET)
 		return 0;
-- 
2.17.1