Commit fb5c2029 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm: Account dirty folios properly during splits 



If the last folio in a file is split as a result of truncation,
we simply clear the dirty bits for the pages we're discarding.
That causes NR_FILE_DIRTY (among other counters) to be thrown off
and eventually Linux will hang in balance_dirty_pages_ratelimited()

Reported-by: default avatarDave Chinner <dchinner@redhat.com>
Tested-by: default avatarDave Chinner <dchinner@redhat.com>
Tested-by: default avatarDarrick J. Wong <djwong@kernel.org>
Fixes: d68eccad ("mm/filemap: Allow large folios to be added to the page cache")
Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
parent 0840a791

mm/huge_memory.c

+8 −3
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/shrinker.h>

#include <linux/mm_inline.h>

#include <linux/swapops.h>

#include <linux/backing-dev.h>

#include <linux/dax.h>

#include <linux/khugepaged.h>

#include <linux/freezer.h>
@@ -2440,11 +2441,15 @@ static void __split_huge_page(struct page *page, struct list_head *list, 
		__split_huge_page_tail(head, i, lruvec, list);

		/* Some pages can be beyond EOF: drop them from page cache */

		if (head[i].index >= end) {

			ClearPageDirty(head + i);

			__delete_from_page_cache(head + i, NULL);

			struct folio *tail = page_folio(head + i);



			if (shmem_mapping(head->mapping))

				shmem_uncharge(head->mapping->host, 1);

			put_page(head + i);

			else if (folio_test_clear_dirty(tail))

				folio_account_cleaned(tail,

					inode_to_wb(folio->mapping->host));

			__filemap_remove_folio(tail, NULL);

			folio_put(tail);

		} else if (!PageAnon(page)) {

			__xa_store(&head->mapping->i_pages, head[i].index,

					head + i, 0);