1 files changed, 18 insertions, 0 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 0ae86ddf221..94b7788c318 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3445,6 +3445,18 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
 #define CIFS_DEFAULT_NON_POSIX_RSIZE (60 * 1024)
 #define CIFS_DEFAULT_NON_POSIX_WSIZE (65536)
 
+/*
+ * On hosts with high memory, we can't currently support wsize/rsize that are
+ * larger than we can kmap at once. Cap the rsize/wsize at
+ * LAST_PKMAP * PAGE_SIZE. We'll never be able to fill a read or write request
+ * larger than that anyway.
+ */
+#ifdef CONFIG_HIGHMEM
+#define CIFS_KMAP_SIZE_LIMIT    (LAST_PKMAP * PAGE_CACHE_SIZE)
+#else /* CONFIG_HIGHMEM */
+#define CIFS_KMAP_SIZE_LIMIT    (1<<24)
+#endif /* CONFIG_HIGHMEM */
+
 static unsigned int
 cifs_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
 {
@@ -3475,6 +3487,9 @@ cifs_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
                 wsize = min_t(unsigned int, wsize,
                                 server->maxBuf - sizeof(WRITE_REQ) + 4);
 
+        /* limit to the amount that we can kmap at once */
+        wsize = min_t(unsigned int, wsize, CIFS_KMAP_SIZE_LIMIT);
+
         /* hard limit of CIFS_MAX_WSIZE */
         wsize = min_t(unsigned int, wsize, CIFS_MAX_WSIZE);
 
@@ -3516,6 +3531,9 @@ cifs_negotiate_rsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
         if (!(server->capabilities & CAP_LARGE_READ_X))
                 rsize = min_t(unsigned int, CIFSMaxBufSize, rsize);
 
+        /* limit to the amount that we can kmap at once */
+        rsize = min_t(unsigned int, rsize, CIFS_KMAP_SIZE_LIMIT);
+
         /* hard limit of CIFS_MAX_RSIZE */
         rsize = min_t(unsigned int, rsize, CIFS_MAX_RSIZE);