From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C6C932D24B7; Mon, 17 Nov 2025 09:48:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763372928; cv=none; b=g8UwuOL9RRaf1gZ7YLkhbRcLrArNHwY7jffSA3KYlNi0T8QA7Njjxex7ch0uWTO7fjO5zCsKAotqE3NDX7IBqkMOfsEA8HM/kADCvF0wCeEUGHcYTj+faZwOBVxn19rkSAC8RJAzAI4WD56d3WTKsfl3bchvQ3LvDOl8KjSGKGw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763372928; c=relaxed/simple; bh=lm1w5FuS0DFB8h8yriOEHrATD1xOM/lURkIhKIQpwx4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CUDlf5qDz+gILLpTna6AFzSlGHzkH01fVeGrL1hejHB/PTj/XXJWGCyKsFsVAUG9Jpd6d+t1yPlTfdCgqmYn8ikai765XijUmZ3xsVDoXvEOmOiavwnf3jQEhqt7O79VO2U36xpkcZlatFKITdgPeAUxXiKdAwsPbSxkDeTCHfI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SXc3AudH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="SXc3AudH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5CEF7C4CEF5; Mon, 17 Nov 2025 09:48:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763372928; bh=lm1w5FuS0DFB8h8yriOEHrATD1xOM/lURkIhKIQpwx4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SXc3AudH1OcuTxWg9OhFFVFP1nWirXtdO1p8OrOMzac+67OuDLkRz4ILPP6fVSALp /FbXlUfKN2ZqyIZO3SFzOhbbbqmC2Z86SKwLoD9XyFGPsHtZU+1VwzcobeHdGPdC5m 54CJLuAlBSE64se+irsZX2F5e70m/vq92kn/oHf3DGlIeWfbhsCCrasmYoDchg7fRR BY4na8GLM3cbXQevPwcrFoOhVgHiO9zWC/7t8Dh0EgtknybsgJlwU8qjyFgFQP+eV3 ZlRWl0ggiJpxxK7ALwoCwBJzw5EWBAi4stEaB7qIPc7tc6pfgp491Hjf3BtbERlnOu LCc5gzOIltBsw== Date: Mon, 17 Nov 2025 11:48:24 +0200 From: Mike Rapoport To: Pasha Tatashin Cc: pratyush@kernel.org, jasonmiu@google.com, graf@amazon.com, dmatlack@google.com, rientjes@google.com, corbet@lwn.net, rdunlap@infradead.org, ilpo.jarvinen@linux.intel.com, kanie@linux.alibaba.com, ojeda@kernel.org, aliceryhl@google.com, masahiroy@kernel.org, akpm@linux-foundation.org, tj@kernel.org, yoann.congal@smile.fr, mmaurer@google.com, roman.gushchin@linux.dev, chenridong@huawei.com, axboe@kernel.dk, mark.rutland@arm.com, jannh@google.com, vincent.guittot@linaro.org, hannes@cmpxchg.org, dan.j.williams@intel.com, david@redhat.com, joel.granados@kernel.org, rostedt@goodmis.org, anna.schumaker@oracle.com, song@kernel.org, linux@weissschuh.net, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, gregkh@linuxfoundation.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, rafael@kernel.org, dakr@kernel.org, bartosz.golaszewski@linaro.org, cw00.choi@samsung.com, myungjoo.ham@samsung.com, yesanishhere@gmail.com, Jonathan.Cameron@huawei.com, quic_zijuhu@quicinc.com, aleksander.lobakin@intel.com, ira.weiny@intel.com, andriy.shevchenko@linux.intel.com, leon@kernel.org, lukas@wunner.de, bhelgaas@google.com, wagi@kernel.org, djeffery@redhat.com, stuart.w.hayes@gmail.com, ptyadav@amazon.de, lennart@poettering.net, brauner@kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, saeedm@nvidia.com, ajayachandra@nvidia.com, jgg@nvidia.com, parav@nvidia.com, leonro@nvidia.com, witu@nvidia.com, hughd@google.com, skhawaja@google.com, chrisl@kernel.org Subject: Re: [PATCH v6 11/20] mm: shmem: use SHMEM_F_* flags instead of VM_* flags Message-ID: References: <20251115233409.768044-1-pasha.tatashin@soleen.com> <20251115233409.768044-12-pasha.tatashin@soleen.com> Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251115233409.768044-12-pasha.tatashin@soleen.com> On Sat, Nov 15, 2025 at 06:33:57PM -0500, Pasha Tatashin wrote: > From: Pratyush Yadav > > 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. > > Signed-off-by: Pratyush Yadav > Signed-off-by: Pasha Tatashin Reviewed-by: Mike Rapoport (Microsoft) > --- > include/linux/shmem_fs.h | 6 ++++++ > mm/shmem.c | 28 +++++++++++++++------------- > 2 files changed, 21 insertions(+), 13 deletions(-) > > diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h > index 0e47465ef0fd..650874b400b5 100644 > --- a/include/linux/shmem_fs.h > +++ b/include/linux/shmem_fs.h > @@ -10,6 +10,7 @@ > #include > #include > #include > +#include > > 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 */ > diff --git a/mm/shmem.c b/mm/shmem.c > index 58701d14dd96..1d5036dec08a 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -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); > -- > 2.52.0.rc1.455.g30608eb744-goog > -- Sincerely yours, Mike.