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| author | Gerald Schaefer <gerald.schaefer@linux.ibm.com> | 2020-12-11 13:36:53 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-11 14:02:14 -0800 |
| commit | ba9c1201beaa86a773e83be5654602a0667e4a4d (patch) | |
| tree | 41874abd9d05ac4fd105f6bb29feca0c065c722d /mm/hugetlb.c | |
| parent | 6c82d45c7f0348b44e00bd7dcccfc47dec7577d1 (diff) | |
| download | lwn-ba9c1201beaa86a773e83be5654602a0667e4a4d.tar.gz lwn-ba9c1201beaa86a773e83be5654602a0667e4a4d.zip | |
mm/hugetlb: clear compound_nr before freeing gigantic pages
Commit 1378a5ee451a ("mm: store compound_nr as well as compound_order")
added compound_nr counter to first tail struct page, overlaying with
page->mapping. The overlay itself is fine, but while freeing gigantic
hugepages via free_contig_range(), a "bad page" check will trigger for
non-NULL page->mapping on the first tail page:
BUG: Bad page state in process bash pfn:380001
page:00000000c35f0856 refcount:0 mapcount:0 mapping:00000000126b68aa index:0x0 pfn:0x380001
aops:0x0
flags: 0x3ffff00000000000()
raw: 3ffff00000000000 0000000000000100 0000000000000122 0000000100000000
raw: 0000000000000000 0000000000000000 ffffffff00000000 0000000000000000
page dumped because: non-NULL mapping
Modules linked in:
CPU: 6 PID: 616 Comm: bash Not tainted 5.10.0-rc7-next-20201208 #1
Hardware name: IBM 3906 M03 703 (LPAR)
Call Trace:
show_stack+0x6e/0xe8
dump_stack+0x90/0xc8
bad_page+0xd6/0x130
free_pcppages_bulk+0x26a/0x800
free_unref_page+0x6e/0x90
free_contig_range+0x94/0xe8
update_and_free_page+0x1c4/0x2c8
free_pool_huge_page+0x11e/0x138
set_max_huge_pages+0x228/0x300
nr_hugepages_store_common+0xb8/0x130
kernfs_fop_write+0xd2/0x218
vfs_write+0xb0/0x2b8
ksys_write+0xac/0xe0
system_call+0xe6/0x288
Disabling lock debugging due to kernel taint
This is because only the compound_order is cleared in
destroy_compound_gigantic_page(), and compound_nr is set to
1U << order == 1 for order 0 in set_compound_order(page, 0).
Fix this by explicitly clearing compound_nr for first tail page after
calling set_compound_order(page, 0).
Link: https://lkml.kernel.org/r/20201208182813.66391-2-gerald.schaefer@linux.ibm.com
Fixes: 1378a5ee451a ("mm: store compound_nr as well as compound_order")
Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: <stable@vger.kernel.org> [5.9+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 37f15c3c24dc..d029d938d26d 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1216,6 +1216,7 @@ static void destroy_compound_gigantic_page(struct page *page, } set_compound_order(page, 0); + page[1].compound_nr = 0; __ClearPageHead(page); } |