+ mm-shmem-return-head-page-from-find_lock_entry-fix.patch added to -mm tree

+ mm-shmem-return-head-page-from-find_lock_entry-fix.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm-shmem-return-head-page-from-find_lock_entry-fix
has been added to the -mm tree.  Its filename is
     mm-shmem-return-head-page-from-find_lock_entry-fix.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-shmem-return-head-page-from-find_lock_entry-fix.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-shmem-return-head-page-from-find_lock_entry-fix.patch

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------------------------------------------------------
From: Matthew Wilcox <willy@infradead.org>
Subject: mm-shmem-return-head-page-from-find_lock_entry-fix

fix BUG()s


[1] https://lore.kernel.org/linux-mm/20200912032042.GA6583@casper.infradead.org/

Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/shmem.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/mm/shmem.c~mm-shmem-return-head-page-from-find_lock_entry-fix
+++ a/mm/shmem.c
@@ -1803,7 +1803,7 @@ static int shmem_getpage_gfp(struct inod
 	struct mm_struct *charge_mm;
 	struct page *page;
 	enum sgp_type sgp_huge = sgp;
-	pgoff_t hindex;
+	pgoff_t hindex = index;
 	int error;
 	int once = 0;
 	int alloced = 0;
@@ -1832,6 +1832,8 @@ repeat:
 		return error;
 	}
 
+	if (page)
+		hindex = page->index;
 	if (page && sgp == SGP_WRITE)
 		mark_page_accessed(page);
 
@@ -1842,6 +1844,7 @@ repeat:
 		unlock_page(page);
 		put_page(page);
 		page = NULL;
+		hindex = index;
 	}
 	if (page || sgp == SGP_READ)
 		goto out;
@@ -1992,7 +1995,7 @@ clear:
 		goto unlock;
 	}
 out:
-	*pagep = page + index - page->index;
+	*pagep = page + index - hindex;
 	return 0;
 
 	/*
_

Patches currently in -mm which might be from willy@infradead.org are

mm-debug-do-not-dereference-i_ino-blindly.patch
mm-factor-find_get_incore_page-out-of-mincore_page.patch
mm-use-find_get_incore_page-in-memcontrol.patch
mm-optimise-madvise-willneed.patch
mm-optimise-madvise-willneed-fix.patch
proc-optimise-smaps-for-shmem-entries.patch
i915-use-find_lock_page-instead-of-find_lock_entry.patch
mm-convert-find_get_entry-to-return-the-head-page.patch
mm-convert-find_get_entry-to-return-the-head-page-fix.patch
mm-shmem-return-head-page-from-find_lock_entry.patch
mm-shmem-return-head-page-from-find_lock_entry-fix.patch
mm-add-find_lock_head.patch
mm-filemap-fix-filemap_map_pages-for-thp.patch
mm-account-pmd-tables-like-pte-tables.patch
mm-move-pagedoublemap-bit.patch
mm-simplify-pagedoublemap-with-pf_second-policy.patch
xarray-add-xa_get_order.patch
xarray-add-xas_split.patch
xarray-add-xas_split-fix-2.patch
mm-filemap-fix-storing-to-a-thp-shadow-entry.patch
mm-filemap-fix-page-cache-removal-for-arbitrary-sized-thps.patch
mm-memory-remove-page-fault-assumption-of-compound-page-size.patch
mm-page_owner-change-split_page_owner-to-take-a-count.patch
mm-huge_memory-fix-page_trans_huge_mapcount-assumption-of-thp-size.patch
mm-huge_memory-fix-can_split_huge_page-assumption-of-thp-size.patch
mm-rmap-fix-assumptions-of-thp-size.patch
mm-truncate-fix-truncation-for-pages-of-arbitrary-size.patch
mm-page-writeback-support-tail-pages-in-wait_for_stable_page.patch
mm-vmscan-allow-arbitrary-sized-pages-to-be-paged-out.patch
mm-readahead-add-define_readahead.patch
mm-readahead-make-page_cache_ra_unbounded-take-a-readahead_control.patch
mm-readahead-make-do_page_cache_ra-take-a-readahead_control.patch
mm-readahead-add-page_cache_sync_ra-and-page_cache_async_ra.patch
harden-autofs-ioctl-table.patch