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mm: shmem: use SHMEM_F_* flags instead of VM_* flags 

shmem_inode_info::flags can have the VM flags VM_NORESERVE and VM_LOCKED. 
These are used to suppress pre-accounting or to lock the pages in the
inode respectively.  Using the VM flags directly makes it difficult to add
shmem-specific flags that are unrelated to VM behavior since one would
need to find a VM flag not used by shmem and re-purpose it.

Introduce SHMEM_F_NORESERVE and SHMEM_F_LOCKED which represent the same
information, but their bits are independent of the VM flags.  Callers can
still pass VM_NORESERVE to shmem_get_inode(), but it gets transformed to
the shmem-specific flag internally.

No functional changes intended.

Link: https://lkml.kernel.org/r/20251125165850.3389713-11-pasha.tatashin@soleen.com
Signed-off-by: Pratyush Yadav <ptyadav@amazon.de>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
pull/1354/merge
Pratyush Yadav 2025-11-25 11:58:40 -05:00 committed by Andrew Morton
parent 7a5afa7ea8
commit 6ff1610ced
2 changed files with 21 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/shmem_fs.h
View File

@ -10,6 +10,7 @@
#include <linux/xattr.h>
#include <linux/fs_parser.h>
#include <linux/userfaultfd_k.h>
#include <linux/bits.h>
struct swap_iocb;
@ -19,6 +20,11 @@ struct swap_iocb;
#define SHMEM_MAXQUOTAS 2
#endif
/* Suppress pre-accounting of the entire object size. */
#define SHMEM_F_NORESERVE BIT(0)
/* Disallow swapping. */
#define SHMEM_F_LOCKED BIT(1)
struct shmem_inode_info {
spinlock_t lock;
unsigned int seals; /* shmem seals */

28
mm/shmem.c
View File

@ -175,20 +175,20 @@ static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
*/
static inline int shmem_acct_size(unsigned long flags, loff_t size)
{
return (flags & VM_NORESERVE) ?
return (flags & SHMEM_F_NORESERVE) ?
0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
}
static inline void shmem_unacct_size(unsigned long flags, loff_t size)
{
if (!(flags & VM_NORESERVE))
if (!(flags & SHMEM_F_NORESERVE))
vm_unacct_memory(VM_ACCT(size));
}
static inline int shmem_reacct_size(unsigned long flags,
loff_t oldsize, loff_t newsize)
{
if (!(flags & VM_NORESERVE)) {
if (!(flags & SHMEM_F_NORESERVE)) {
if (VM_ACCT(newsize) > VM_ACCT(oldsize))
return security_vm_enough_memory_mm(current->mm,
VM_ACCT(newsize) - VM_ACCT(oldsize));
@ -206,7 +206,7 @@ static inline int shmem_reacct_size(unsigned long flags,
*/
static inline int shmem_acct_blocks(unsigned long flags, long pages)
{
if (!(flags & VM_NORESERVE))
if (!(flags & SHMEM_F_NORESERVE))
return 0;
return security_vm_enough_memory_mm(current->mm,
@ -215,7 +215,7 @@ static inline int shmem_acct_blocks(unsigned long flags, long pages)
static inline void shmem_unacct_blocks(unsigned long flags, long pages)
{
if (flags & VM_NORESERVE)
if (flags & SHMEM_F_NORESERVE)
vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
}
@ -1551,7 +1551,7 @@ int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
int nr_pages;
bool split = false;
if ((info->flags & VM_LOCKED) || sbinfo->noswap)
if ((info->flags & SHMEM_F_LOCKED) || sbinfo->noswap)
goto redirty;
if (!total_swap_pages)
@ -2910,15 +2910,15 @@ int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
* ipc_lock_object() when called from shmctl_do_lock(),
* no serialization needed when called from shm_destroy().
*/
if (lock && !(info->flags & VM_LOCKED)) {
if (lock && !(info->flags & SHMEM_F_LOCKED)) {
if (!user_shm_lock(inode->i_size, ucounts))
goto out_nomem;
info->flags |= VM_LOCKED;
info->flags |= SHMEM_F_LOCKED;
mapping_set_unevictable(file->f_mapping);
}
if (!lock && (info->flags & VM_LOCKED) && ucounts) {
if (!lock && (info->flags & SHMEM_F_LOCKED) && ucounts) {
user_shm_unlock(inode->i_size, ucounts);
info->flags &= ~VM_LOCKED;
info->flags &= ~SHMEM_F_LOCKED;
mapping_clear_unevictable(file->f_mapping);
}
retval = 0;
@ -3062,7 +3062,7 @@ static struct inode *__shmem_get_inode(struct mnt_idmap *idmap,
spin_lock_init(&info->lock);
atomic_set(&info->stop_eviction, 0);
info->seals = F_SEAL_SEAL;
info->flags = flags & VM_NORESERVE;
info->flags = (flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
info->i_crtime = inode_get_mtime(inode);
info->fsflags = (dir == NULL) ? 0 :
SHMEM_I(dir)->fsflags & SHMEM_FL_INHERITED;
@ -5804,8 +5804,10 @@ static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
/* common code */
static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name,
loff_t size, unsigned long flags, unsigned int i_flags)
loff_t size, unsigned long vm_flags,
unsigned int i_flags)
{
unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
struct inode *inode;
struct file *res;
@ -5822,7 +5824,7 @@ static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name,
return ERR_PTR(-ENOMEM);
inode = shmem_get_inode(&nop_mnt_idmap, mnt->mnt_sb, NULL,
S_IFREG | S_IRWXUGO, 0, flags);
S_IFREG | S_IRWXUGO, 0, vm_flags);
if (IS_ERR(inode)) {
shmem_unacct_size(flags, size);
return ERR_CAST(inode);