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PM: hibernate: Clean up sync_read handling in snapshot_write_next()
commitd08970df19
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:8357376d3d
("[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>
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1 changed files with 1 additions and 5 deletions
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@ -2591,8 +2591,6 @@ int snapshot_write_next(struct snapshot_handle *handle)
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if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages)
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return 0;
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handle->sync_read = 1;
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if (!handle->cur) {
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if (!buffer)
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/* This makes the buffer be freed by swsusp_free() */
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@ -2633,7 +2631,6 @@ int snapshot_write_next(struct snapshot_handle *handle)
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memory_bm_position_reset(&orig_bm);
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restore_pblist = NULL;
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handle->buffer = get_buffer(&orig_bm, &ca);
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handle->sync_read = 0;
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if (IS_ERR(handle->buffer))
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return PTR_ERR(handle->buffer);
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}
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@ -2645,9 +2642,8 @@ int snapshot_write_next(struct snapshot_handle *handle)
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handle->buffer = get_buffer(&orig_bm, &ca);
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if (IS_ERR(handle->buffer))
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return PTR_ERR(handle->buffer);
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if (handle->buffer != buffer)
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handle->sync_read = 0;
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}
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handle->sync_read = (handle->buffer == buffer);
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handle->cur++;
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return PAGE_SIZE;
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}
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