4.19-stable review patch. If anyone has any objections, please let me know.
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From: Brian Geffon bgeffon@google.com
commit d08970df1980476f27936e24d452550f3e9e92e1 upstream.
In snapshot_write_next(), sync_read is set and unset in three different spots unnecessiarly. As a result there is a subtle bug where the first page after the meta data has been loaded unconditionally sets sync_read to 0. If this first PFN was actually a highmem page, then the returned buffer will be the global "buffer," and the page needs to be loaded synchronously.
That is, I'm not sure we can always assume the following to be safe:
handle->buffer = get_buffer(&orig_bm, &ca); handle->sync_read = 0;
Because get_buffer() can call get_highmem_page_buffer() which can return 'buffer'.
The easiest way to address this is just set sync_read before snapshot_write_next() returns if handle->buffer == buffer.
Signed-off-by: Brian Geffon bgeffon@google.com Fixes: 8357376d3df2 ("[PATCH] swsusp: Improve handling of highmem") Cc: All applicable stable@vger.kernel.org [ rjw: Subject and changelog edits ] Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/power/snapshot.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)
--- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -2591,8 +2591,6 @@ int snapshot_write_next(struct snapshot_ if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages) return 0;
- handle->sync_read = 1; - if (!handle->cur) { if (!buffer) /* This makes the buffer be freed by swsusp_free() */ @@ -2633,7 +2631,6 @@ int snapshot_write_next(struct snapshot_ memory_bm_position_reset(&orig_bm); restore_pblist = NULL; handle->buffer = get_buffer(&orig_bm, &ca); - handle->sync_read = 0; if (IS_ERR(handle->buffer)) return PTR_ERR(handle->buffer); } @@ -2645,9 +2642,8 @@ int snapshot_write_next(struct snapshot_ handle->buffer = get_buffer(&orig_bm, &ca); if (IS_ERR(handle->buffer)) return PTR_ERR(handle->buffer); - if (handle->buffer != buffer) - handle->sync_read = 0; } + handle->sync_read = (handle->buffer == buffer); handle->cur++; return PAGE_SIZE; }