linux-kernel - Re: [PATCH v1 25/32] mm: shmem: use SHMEM_F_* flags instead of VM

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <mafs01pr6u06u.fsf@kernel.org>
Date: Thu, 26 Jun 2025 15:00:57 +0200
From: Pratyush Yadav <pratyush@...nel.org>
To: Pasha Tatashin <pasha.tatashin@...een.com>
Cc: pratyush@...nel.org,  jasonmiu@...gle.com,  graf@...zon.com,
  changyuanl@...gle.com,  rppt@...nel.org,  dmatlack@...gle.com,
  rientjes@...gle.com,  corbet@....net,  rdunlap@...radead.org,
  ilpo.jarvinen@...ux.intel.com,  kanie@...ux.alibaba.com,
  ojeda@...nel.org,  aliceryhl@...gle.com,  masahiroy@...nel.org,
  akpm@...ux-foundation.org,  tj@...nel.org,  yoann.congal@...le.fr,
  mmaurer@...gle.com,  roman.gushchin@...ux.dev,  chenridong@...wei.com,
  axboe@...nel.dk,  mark.rutland@....com,  jannh@...gle.com,
  vincent.guittot@...aro.org,  hannes@...xchg.org,
  dan.j.williams@...el.com,  david@...hat.com,  joel.granados@...nel.org,
  rostedt@...dmis.org,  anna.schumaker@...cle.com,  song@...nel.org,
  zhangguopeng@...inos.cn,  linux@...ssschuh.net,
  linux-kernel@...r.kernel.org,  linux-doc@...r.kernel.org,
  linux-mm@...ck.org,  gregkh@...uxfoundation.org,  tglx@...utronix.de,
  mingo@...hat.com,  bp@...en8.de,  dave.hansen@...ux.intel.com,
  x86@...nel.org,  hpa@...or.com,  rafael@...nel.org,  dakr@...nel.org,
  bartosz.golaszewski@...aro.org,  cw00.choi@...sung.com,
  myungjoo.ham@...sung.com,  yesanishhere@...il.com,
  Jonathan.Cameron@...wei.com,  quic_zijuhu@...cinc.com,
  aleksander.lobakin@...el.com,  ira.weiny@...el.com,
  andriy.shevchenko@...ux.intel.com,  leon@...nel.org,  lukas@...ner.de,
  bhelgaas@...gle.com,  wagi@...nel.org,  djeffery@...hat.com,
  stuart.w.hayes@...il.com,  lennart@...ttering.net,  brauner@...nel.org,
  linux-api@...r.kernel.org,  linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v1 25/32] mm: shmem: use SHMEM_F_* flags instead of VM_*
 flags

Hi all,

On Wed, Jun 25 2025, Pasha Tatashin wrote:

> From: Pratyush Yadav <ptyadav@...zon.de>
>
> 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.

I was reading through this patch again and just realized that I missed a
spot. __shmem_file_setup() passes VM flags to shmem_{un,}acct_size(),
even though it now expects SHMEM_F flag. Below fixup patch should fix
that.

--- 8< ---
>From d027524e390de15af1c6d9310bf6bea0194be79f Mon Sep 17 00:00:00 2001
From: Pratyush Yadav <ptyadav@...zon.de>
Date: Thu, 26 Jun 2025 14:50:27 +0200
Subject: [PATCH] fixup! mm: shmem: use SHMEM_F_* flags instead of VM_* flags

Signed-off-by: Pratyush Yadav <ptyadav@...zon.de>
---
 mm/shmem.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 6b13eb40e7dc2..83ae446f779ef 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -5809,8 +5809,10 @@ 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;
 
@@ -5827,7 +5829,7 @@ 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);
-- 
Regards,
Pratyush Yadav