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Roman Gushchin bcfe06bf26 mm: memcontrol: Use helpers to read page's memcg data 
Patch series "mm: allow mapping accounted kernel pages to userspace", v6.

Currently a non-slab kernel page which has been charged to a memory cgroup
can't be mapped to userspace.  The underlying reason is simple: PageKmemcg
flag is defined as a page type (like buddy, offline, etc), so it takes a
bit from a page->mapped counter.  Pages with a type set can't be mapped to
userspace.

But in general the kmemcg flag has nothing to do with mapping to
userspace.  It only means that the page has been accounted by the page
allocator, so it has to be properly uncharged on release.

Some bpf maps are mapping the vmalloc-based memory to userspace, and their
memory can't be accounted because of this implementation detail.

This patchset removes this limitation by moving the PageKmemcg flag into
one of the free bits of the page->mem_cgroup pointer.  Also it formalizes
accesses to the page->mem_cgroup and page->obj_cgroups using new helpers,
adds several checks and removes a couple of obsolete functions.  As the
result the code became more robust with fewer open-coded bit tricks.

This patch (of 4):

Currently there are many open-coded reads of the page->mem_cgroup pointer,
as well as a couple of read helpers, which are barely used.

It creates an obstacle on a way to reuse some bits of the pointer for
storing additional bits of information.  In fact, we already do this for
slab pages, where the last bit indicates that a pointer has an attached
vector of objcg pointers instead of a regular memcg pointer.

This commits uses 2 existing helpers and introduces a new helper to
converts all read sides to calls of these helpers:
  struct mem_cgroup *page_memcg(struct page *page);
  struct mem_cgroup *page_memcg_rcu(struct page *page);
  struct mem_cgroup *page_memcg_check(struct page *page);

page_memcg_check() is intended to be used in cases when the page can be a
slab page and have a memcg pointer pointing at objcg vector.  It does
check the lowest bit, and if set, returns NULL.  page_memcg() contains a
VM_BUG_ON_PAGE() check for the page not being a slab page.

To make sure nobody uses a direct access, struct page's
mem_cgroup/obj_cgroups is converted to unsigned long memcg_data.

Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Link: https://lkml.kernel.org/r/20201027001657.3398190-1-guro@fb.com
Link: https://lkml.kernel.org/r/20201027001657.3398190-2-guro@fb.com
Link: https://lore.kernel.org/bpf/20201201215900.3569844-2-guro@fb.com
2020-12-02 18:28:05 -08:00
..
9p Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
adfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
affs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
afs afs: Fix incorrect freeing of the ACL passed to the YFS ACL store op 2020-11-03 09:53:40 -08:00
autofs autofs: harden ioctl table 2020-10-16 11:11:22 -07:00
befs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
bfs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
btrfs for-5.10-rc3-tag 2020-11-10 10:07:15 -08:00
cachefiles cachefiles: Handle readpage error correctly 2020-10-26 10:42:54 -07:00
ceph ceph: check session state after bumping session->s_seq 2020-11-04 20:55:49 +01:00
cifs cifs: update internal module version number 2020-10-23 23:41:49 -05:00
coda docs: filesystems: convert coda.txt to ReST 2020-05-05 09:22:21 -06:00
configfs fs: configfs: delete repeated words in comments 2020-10-16 11:11:19 -07:00
cramfs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
crypto fscrypt: remove reachable WARN in fscrypt_setup_iv_ino_lblk_32_key() 2020-11-06 09:48:55 -08:00
debugfs debugfs: remove return value of debugfs_create_devm_seqfile() 2020-10-30 08:37:39 +01:00
devpts
dlm networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
ecryptfs mm, treewide: rename kzfree() to kfree_sensitive() 2020-08-07 11:33:22 -07:00
efivarfs efivarfs: Replace invalid slashes with exclamation marks in dentries. 2020-09-25 23:29:04 +02:00
efs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
erofs erofs: fix setting up pcluster for temporary pages 2020-11-04 09:15:48 +08:00
exfat Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
exportfs
ext2 Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
ext4 ext4: fix sparse warnings in fast_commit code 2020-11-07 00:08:23 -05:00
f2fs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
fat [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
freevxfs
fscache Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2020-06-03 16:27:18 -07:00
fuse fuse update for 5.10 2020-10-19 14:28:30 -07:00
gfs2 gfs2: Wake up when sd_glock_disposal becomes zero 2020-11-03 14:39:11 +01:00
hfs fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
hfsplus fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
hostfs
hpfs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
hugetlbfs hugetlbfs: prevent filesystem stacking of hugetlbfs 2020-08-12 10:57:56 -07:00
iomap mm: memcontrol: Use helpers to read page's memcg data 2020-12-02 18:28:05 -08:00
isofs fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
jbd2 jbd2: fix up sparse warnings in checkpoint code 2020-11-07 00:09:08 -05:00
jffs2 treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
jfs fs: Introduce i_blocks_per_page 2020-09-21 08:59:26 -07:00
kernfs fsnotify: pass dir and inode arguments to fsnotify() 2020-07-27 23:15:48 +02:00
lockd The one new feature this time, from Anna Schumaker, is READ_PLUS, which 2020-10-22 09:44:27 -07:00
minix [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
nfs NFS: Remove unnecessary inode lock in nfs_fsync_dir() 2020-11-12 10:41:26 -05:00
nfs_common NFSv4.2: Fix NFS4ERR_STALE error when doing inter server copy 2020-10-21 10:31:20 -04:00
nfsd NFSD: fix missing refcount in nfsd4_copy by nfsd4_do_async_copy 2020-11-05 17:25:14 -05:00
nilfs2 Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
nls treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
notify mm, memcg: rework remote charging API to support nesting 2020-10-18 09:27:09 -07:00
ntfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
ocfs2 jbd2: rename j_maxlen to j_total_len and add jbd2_journal_max_txn_bufs 2020-11-06 23:01:02 -05:00
omfs fs: omfs: use kmemdup() rather than kmalloc+memcpy 2020-09-22 23:39:45 -04:00
openpromfs
orangefs orangefs: remove unnecessary assignment to variable ret 2020-08-04 15:01:58 -04:00
overlayfs ovl: use generic vfs_ioc_setflags_prepare() helper 2020-10-06 15:38:15 +02:00
proc Merge branch 'hch' (patches from Christoph) 2020-11-08 10:11:31 -08:00
pstore treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
qnx4 [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
qnx6 [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
quota \n 2020-10-15 14:56:15 -07:00
ramfs ramfs: fix nommu mmap with gaps in the page cache 2020-10-16 11:11:22 -07:00
reiserfs reiserfs: Fix oops during mount 2020-10-01 11:15:31 +02:00
romfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
squashfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
sysfs sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-10-02 12:02:30 +02:00
sysv [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
tracefs
ubifs This pull request contains fixes for UBI and UBIFS 2020-10-18 09:56:50 -07:00
udf Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
ufs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
unicode unicode: Add utf8_casefold_hash 2020-09-10 14:03:31 -07:00
vboxsf Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2020-10-15 15:11:56 -07:00
verity fs-verity: use smp_load_acquire() for ->i_verity_info 2020-07-21 16:02:41 -07:00
xfs xfs: only flush the unshared range in xfs_reflink_unshare 2020-11-04 17:41:56 -08:00
zonefs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
aio.c Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-12 16:35:51 -07:00
anon_inodes.c
attr.c
bad_inode.c fs: move the fiemap definitions out of fs.h 2020-06-03 23:16:55 -04:00
binfmt_aout.c exec: Rename flush_old_exec begin_new_exec 2020-05-07 16:55:47 -05:00
binfmt_elf_fdpic.c binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot 2020-10-16 11:11:21 -07:00
binfmt_elf.c fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
binfmt_em86.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
binfmt_flat.c binfmt_flat: revert "binfmt_flat: don't offset the data start" 2020-08-24 08:49:13 +10:00
binfmt_misc.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
binfmt_script.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
block_dev.c block: add a bdget_part helper 2020-10-05 10:38:33 -06:00
buffer.c mm: memcontrol: Use helpers to read page's memcg data 2020-12-02 18:28:05 -08:00
char_dev.c vfs: allow unprivileged whiteout creation 2020-05-14 16:44:23 +02:00
compat_binfmt_elf.c Split the old READ_IMPLIES_EXEC workaround from executable PT_GNU_STACK 2020-06-05 13:45:21 -07:00
coredump.c binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot 2020-10-16 11:11:21 -07:00
d_path.c fs: fix NULL dereference due to data race in prepend_path() 2020-10-14 14:54:45 -07:00
dax.c fuse update for 5.10 2020-10-19 14:28:30 -07:00
dcache.c vfs: Use sequence counter with associated spinlock 2020-07-29 16:14:27 +02:00
dcookies.c
direct-io.c \n 2020-10-15 15:03:10 -07:00
drop_caches.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
eventfd.c eventfd: convert to f_op->read_iter() 2020-05-06 22:33:43 -04:00
eventpoll.c net: Add SO_BUSY_POLL_BUDGET socket option 2020-12-01 00:09:25 +01:00
exec.c powerpc updates for 5.10 2020-10-16 12:21:15 -07:00
fcntl.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
fhandle.c
file_table.c task_work: cleanup notification modes 2020-10-17 15:05:30 -06:00
file.c io_uring: don't rely on weak ->files references 2020-09-30 20:32:32 -06:00
filesystems.c fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once() 2020-04-10 15:36:22 -07:00
fs_context.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
fs_parser.c fs_parse: mark fs_param_bad_value() as static 2020-10-13 18:38:27 -07:00
fs_pin.c
fs_struct.c vfs: Use sequence counter with associated spinlock 2020-07-29 16:14:27 +02:00
fs_types.c
fs-writeback.c block-5.10-2020-10-12 2020-10-13 12:12:44 -07:00
fsopen.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
init.c init: add an init_dup helper 2020-08-04 21:02:38 -04:00
inode.c fs: add a filesystem flag for THPs 2020-10-16 11:11:15 -07:00
internal.h fs: remove compat_sys_mount 2020-09-22 23:45:57 -04:00
io_uring.c io_uring: fix link lookup racing with link timeout 2020-11-05 15:36:40 -07:00
io-wq.c io-wq: cancel request if it's asking for files and we don't have them 2020-11-04 10:22:56 -07:00
io-wq.h io_uring: unify fsize with def->work_flags 2020-10-20 16:03:13 -06:00
ioctl.c fs: remove ksys_ioctl 2020-07-31 08:16:01 +02:00
Kconfig tmpfs: support 64-bit inums per-sb 2020-08-07 11:33:24 -07:00
Kconfig.binfmt treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
kernel_read_file.c fs/kernel_file_read: Add "offset" arg for partial reads 2020-10-05 13:37:04 +02:00
libfs.c fs: Add standard casefolding support 2020-09-10 14:03:31 -07:00
locks.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
Makefile Refactored code for 5.10: 2020-10-23 11:33:41 -07:00
mbcache.c
mount.h proc/mounts: add cursor 2020-05-14 16:44:24 +02:00
mpage.c fs: convert mpage_readpages to mpage_readahead 2020-06-02 10:59:07 -07:00
namei.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
namespace.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
no-block.c
nsfs.c nsproxy: attach to namespaces via pidfds 2020-05-13 11:41:22 +02:00
open.c exec: move S_ISREG() check earlier 2020-08-12 10:58:01 -07:00
pipe.c Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-11 11:11:35 -07:00
pnode.c propagate_one(): mnt_set_mountpoint() needs mount_lock 2020-04-27 10:37:14 -04:00
pnode.h
posix_acl.c vfs: clean up posix_acl_permission() logic aroudn MAY_NOT_BLOCK 2020-06-08 11:04:19 -07:00
proc_namespace.c Add a "nosymfollow" mount option. 2020-08-27 16:06:47 -04:00
read_write.c Refactored code for 5.10: 2020-10-23 11:33:41 -07:00
readdir.c fs: remove ksys_getdents64 2020-07-31 08:16:00 +02:00
remap_range.c vfs: move the remap range helpers to remap_range.c 2020-10-15 09:48:49 -07:00
select.c fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
seq_file.c seq_file: add seq_read_iter 2020-11-06 10:05:18 -08:00
signalfd.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
splice.c io_uring-5.10-2020-10-24 2020-10-24 12:40:18 -07:00
stack.c
stat.c fs: remove KSTAT_QUERY_FLAGS 2020-09-26 22:55:05 -04:00
statfs.c Add a "nosymfollow" mount option. 2020-08-27 16:06:47 -04:00
super.c bdi: replace BDI_CAP_STABLE_WRITES with a queue and a sb flag 2020-09-24 13:43:39 -06:00
sync.c overlayfs update for 5.8 2020-06-09 15:40:50 -07:00
timerfd.c
userfaultfd.c mm: remove the now-unnecessary mmget_still_valid() hack 2020-10-16 11:11:22 -07:00
utimes.c fs: expose utimes_common 2020-07-31 08:16:01 +02:00
xattr.c fs/xattr.c: fix kernel-doc warnings for setxattr & removexattr 2020-10-13 18:38:27 -07:00