mm: vmscan: lock page on swap error in pageout (81332eca) · Commits · e / devices / android_kernel_sony_msm8994

A workaround was added ealier to move a page to active list if swapping to devices like zram fails. But this can result in try_to_free_swap being called from shrink_page_list, without a properly locked page. Lock the page when we indicate to activate a page in pageout(). Add a check to ensure that error is on swap, and clear the error flag before moving the page to active list. CRs-fixed: 760049 Change-Id: I77a8bbd6ed13efdec943298fe9448412feeac176 Signed-off-by:

Vinayak Menon <vinmenon@codeaurora.org>

mm/vmscan.c

+11 −1

Original line number	Diff line number	Diff line
		@@ -507,9 +507,19 @@ static pageout_t pageout(struct page page, struct address_space mapping,
		if (!PageWriteback(page)) {
		/* synchronous write or broken a_ops? */
		ClearPageReclaim(page);
		if (PageError(page))
		if (PageError(page) && PageSwapCache(page)) {
		ClearPageError(page);
		/*
		* We lock the page here because it is required
		* to free the swp space later in
		* shrink_page_list. But the page may be
		* unclocked by functions like
		* handle_write_error.
		*/
		__set_page_locked(page);
		return PAGE_ACTIVATE;
		}
		}
		trace_mm_vmscan_writepage(page, trace_reclaim_flags(page));
		inc_zone_page_state(page, NR_VMSCAN_WRITE);
		return PAGE_SUCCESS;