diff options
| author | Jinjiang Tu <tujinjiang@huawei.com> | 2025-09-29 16:34:23 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-10-02 13:35:48 +0200 |
| commit | 91f548e920fbf8be3f285bfa3fa045ae017e836d (patch) | |
| tree | 863cacc7c8148e714eaa0d286df4f156a9e96f42 | |
| parent | f47876788a23de296c42ef9d505b5c1630f0b4b8 (diff) | |
mm/hugetlb: fix folio is still mapped when deleted
[ Upstream commit 7b7387650dcf2881fd8bb55bcf3c8bd6c9542dd7 ]
Migration may be raced with fallocating hole. remove_inode_single_folio
will unmap the folio if the folio is still mapped. However, it's called
without folio lock. If the folio is migrated and the mapped pte has been
converted to migration entry, folio_mapped() returns false, and won't
unmap it. Due to extra refcount held by remove_inode_single_folio,
migration fails, restores migration entry to normal pte, and the folio is
mapped again. As a result, we triggered BUG in filemap_unaccount_folio.
The log is as follows:
BUG: Bad page cache in process hugetlb pfn:156c00
page: refcount:515 mapcount:0 mapping:0000000099fef6e1 index:0x0 pfn:0x156c00
head: order:9 mapcount:1 entire_mapcount:1 nr_pages_mapped:0 pincount:0
aops:hugetlbfs_aops ino:dcc dentry name(?):"my_hugepage_file"
flags: 0x17ffffc00000c1(locked|waiters|head|node=0|zone=2|lastcpupid=0x1fffff)
page_type: f4(hugetlb)
page dumped because: still mapped when deleted
CPU: 1 UID: 0 PID: 395 Comm: hugetlb Not tainted 6.17.0-rc5-00044-g7aac71907bde-dirty #484 NONE
Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
Call Trace:
<TASK>
dump_stack_lvl+0x4f/0x70
filemap_unaccount_folio+0xc4/0x1c0
__filemap_remove_folio+0x38/0x1c0
filemap_remove_folio+0x41/0xd0
remove_inode_hugepages+0x142/0x250
hugetlbfs_fallocate+0x471/0x5a0
vfs_fallocate+0x149/0x380
Hold folio lock before checking if the folio is mapped to avold race with
migration.
Link: https://lkml.kernel.org/r/20250912074139.3575005-1-tujinjiang@huawei.com
Fixes: 4aae8d1c051e ("mm/hugetlbfs: unmap pages if page fault raced with hole punch")
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ folio -> page ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/hugetlbfs/inode.c | 14 |
1 files changed, 6 insertions, 8 deletions
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 6e97a54ffda1..306da7cb3d8b 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -515,13 +515,13 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart, /* * If page is mapped, it was faulted in after being - * unmapped in caller. Unmap (again) now after taking - * the fault mutex. The mutex will prevent faults - * until we finish removing the page. - * - * This race can only happen in the hole punch case. - * Getting here in a truncate operation is a bug. + * unmapped in caller or hugetlb_vmdelete_list() skips + * unmapping it due to fail to grab lock. Unmap (again) + * while holding the fault mutex. The mutex will prevent + * faults until we finish removing the page. Hold page + * lock to guarantee no concurrent migration. */ + lock_page(page); if (unlikely(page_mapped(page))) { BUG_ON(truncate_op); @@ -533,8 +533,6 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart, (index + 1) * pages_per_huge_page(h)); i_mmap_unlock_write(mapping); } - - lock_page(page); /* * We must free the huge page and remove from page * cache (remove_huge_page) BEFORE removing the |