[PATCH AUTOSEL 4.9 09/13] cifs: Fix double add page to memcg when cifs_readpages

Sasha Levin
2020-07-02T01:28:24Z

From: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>

[ Upstream commit 95a3d8f3af9b0d63b43f221b630beaab9739d13a ]

When xfstests generic/451, there is an BUG at mm/memcontrol.c:
page:ffffea000560f2c0 refcount:2 mapcount:0 mapping:000000008544e0ea
index:0xf
mapping->aops:cifs_addr_ops dentry name:"tst-aio-dio-cycle-write.451"
flags: 0x2fffff80000001(locked)
raw: 002fffff80000001 ffffc90002023c50 ffffea0005280088 ffff88815cda0210
raw: 000000000000000f 0000000000000000 00000002ffffffff ffff88817287d000
page dumped because: VM_BUG_ON_PAGE(page->mem_cgroup)
page->mem_cgroup:ffff88817287d000
------------[ cut here ]------------
kernel BUG at mm/memcontrol.c:2659!
invalid opcode: 0000 [#1] SMP
CPU: 2 PID: 2038 Comm: xfs_io Not tainted 5.8.0-rc1 #44
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_
073836-buildvm-ppc64le-16.ppc.4
RIP: 0010:commit_charge+0x35/0x50
Code: 0d 48 83 05 54 b2 02 05 01 48 89 77 38 c3 48 c7
c6 78 4a ea ba 48 83 05 38 b2 02 05 01 e8 63 0d9
RSP: 0018:ffffc90002023a50 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff88817287d000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff88817ac97ea0 RDI: ffff88817ac97ea0
RBP: ffffea000560f2c0 R08: 0000000000000203 R09: 0000000000000005
R10: 0000000000000030 R11: ffffc900020237a8 R12: 0000000000000000
R13: 0000000000000001 R14: 0000000000000001 R15: ffff88815a1272c0
FS: 00007f5071ab0800(0000) GS:ffff88817ac80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055efcd5ca000 CR3: 000000015d312000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
mem_cgroup_charge+0x166/0x4f0
__add_to_page_cache_locked+0x4a9/0x710
add_to_page_cache_locked+0x15/0x20
cifs_readpages+0x217/0x1270
read_pages+0x29a/0x670
page_cache_readahead_unbounded+0x24f/0x390
__do_page_cache_readahead+0x3f/0x60
ondemand_readahead+0x1f1/0x470
page_cache_async_readahead+0x14c/0x170
generic_file_buffered_read+0x5df/0x1100
generic_file_read_iter+0x10c/0x1d0
cifs_strict_readv+0x139/0x170
new_sync_read+0x164/0x250
__vfs_read+0x39/0x60
vfs_read+0xb5/0x1e0
ksys_pread64+0x85/0xf0
__x64_sys_pread64+0x22/0x30
do_syscall_64+0x69/0x150
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f5071fcb1af
Code: Bad RIP value.
RSP: 002b:00007ffde2cdb8e0 EFLAGS: 00000293 ORIG_RAX: 0000000000000011
RAX: ffffffffffffffda RBX: 00007ffde2cdb990 RCX: 00007f5071fcb1af
RDX: 0000000000001000 RSI: 000055efcd5ca000 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000001000 R11: 0000000000000293 R12: 0000000000000001
R13: 000000000009f000 R14: 0000000000000000 R15: 0000000000001000
Modules linked in:
---[ end trace 725fa14a3e1af65c ]---

Since commit 3fea5a499d57 ("mm: memcontrol: convert page cache to a new
mem_cgroup_charge() API") not cancel the page charge, the pages maybe
double add to pagecache:
thread1 | thread2
cifs_readpages
readpages_get_pages
add_to_page_cache_locked(head,index=n)=0
| readpages_get_pages
| add_to_page_cache_locked(head,index=n+1)=0
add_to_page_cache_locked(head, index=n+1)=-EEXIST
then, will next loop with list head page's
index=n+1 and the page->mapping not NULL
readpages_get_pages
add_to_page_cache_locked(head, index=n+1)
commit_charge
VM_BUG_ON_PAGE

So, we should not do the next loop when any page add to page cache
failed.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cifs/file.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index b2919166855f5..385567cae664a 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3531,7 +3531,8 @@ readpages_get_pages(struct address_space *mapping, struct list_head *page_list,
break;

__SetPageLocked(page);
- if (add_to_page_cache_locked(page, mapping, page->index, gfp)) {
+ rc = add_to_page_cache_locked(page, mapping, page->index, gfp);
+ if (rc) {
__ClearPageLocked(page);
break;
}
@@ -3547,6 +3548,7 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
struct list_head *page_list, unsigned num_pages)
{
int rc;
+ int err = 0;
struct list_head tmplist;
struct cifsFileInfo *open_file = file->private_data;
struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(file);
@@ -3587,7 +3589,7 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
* the order of declining indexes. When we put the pages in
* the rdata->pages, then we want them in increasing order.
*/
- while (!list_empty(page_list)) {
+ while (!list_empty(page_list) && !err) {
unsigned int i, nr_pages, bytes, rsize;
loff_t offset;
struct page *page, *tpage;
@@ -3610,9 +3612,10 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
return 0;
}

- rc = readpages_get_pages(mapping, page_list, rsize, &tmplist,
+ nr_pages = 0;
+ err = readpages_get_pages(mapping, page_list, rsize, &tmplist,
&nr_pages, &offset, &bytes);
- if (rc) {
+ if (!nr_pages) {
add_credits_and_wake_if(server, credits, 0);
break;
}
--
2.25.1