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Message-ID: <CAJd=RBBXExVfnHnqWL8Q2zAU5qPCc-qZFKpXPLc+47ey5g_Ukw@mail.gmail.com>
Date: Sun, 4 Mar 2012 11:50:36 +0800
From: Hillf Danton <dhillf@...il.com>
To: Steven Truelove <steven.truelove@...ronto.ca>
Cc: wli@...omorphy.com, akpm@...ux-foundation.org,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] Correct alignment of huge page requests.
On Fri, Mar 2, 2012 at 10:58 AM, Steven Truelove
<steven.truelove@...ronto.ca> wrote:
> When calling shmget() with SHM_HUGETLB, shmget aligns the request size to PAGE_SIZE, but this is not sufficient. Modified hugetlb_file_setup() to align requests to the huge page size, and to accept an address argument so that all alignment checks can be performed in hugetlb_file_setup(), rather than in its callers. Changed newseg and mmap_pgoff to match new prototype and eliminated a now redundant alignment check.
>
> Signed-off-by: Steven Truelove <steven.truelove@...ronto.ca>
Acked-by: Hillf Danton <dhillf@...il.com>
> ---
> fs/hugetlbfs/inode.c | 12 ++++++++----
> include/linux/hugetlb.h | 3 ++-
> ipc/shm.c | 2 +-
> mm/mmap.c | 6 +++---
> 4 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index 1e85a7a..a97b7cc 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -928,7 +928,7 @@ static int can_do_hugetlb_shm(void)
> return capable(CAP_IPC_LOCK) || in_group_p(sysctl_hugetlb_shm_group);
> }
>
> -struct file *hugetlb_file_setup(const char *name, size_t size,
> +struct file *hugetlb_file_setup(const char *name, unsigned long addr, size_t size,
> vm_flags_t acctflag,
> struct user_struct **user, int creat_flags)
> {
> @@ -938,6 +938,8 @@ struct file *hugetlb_file_setup(const char *name, size_t size,
> struct path path;
> struct dentry *root;
> struct qstr quick_string;
> + struct hstate *hstate;
> + int num_pages;
>
> *user = NULL;
> if (!hugetlbfs_vfsmount)
> @@ -967,10 +969,12 @@ struct file *hugetlb_file_setup(const char *name, size_t size,
> if (!inode)
> goto out_dentry;
>
> + hstate = hstate_inode(inode);
> + size += addr & ~huge_page_mask(hstate);
> + num_pages = ALIGN(size, huge_page_size(hstate)) >>
> + huge_page_shift(hstate);
> error = -ENOMEM;
> - if (hugetlb_reserve_pages(inode, 0,
> - size >> huge_page_shift(hstate_inode(inode)), NULL,
> - acctflag))
> + if (hugetlb_reserve_pages(inode, 0, num_pages, NULL, acctflag))
> goto out_inode;
>
> d_instantiate(path.dentry, inode);
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index d9d6c86..4b9e59d 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -164,7 +164,8 @@ static inline struct hugetlbfs_sb_info *HUGETLBFS_SB(struct super_block *sb)
>
> extern const struct file_operations hugetlbfs_file_operations;
> extern const struct vm_operations_struct hugetlb_vm_ops;
> -struct file *hugetlb_file_setup(const char *name, size_t size, vm_flags_t acct,
> +struct file *hugetlb_file_setup(const char *name, unsigned long addr,
> + size_t size, vm_flags_t acct,
> struct user_struct **user, int creat_flags);
> int hugetlb_get_quota(struct address_space *mapping, long delta);
> void hugetlb_put_quota(struct address_space *mapping, long delta);
> diff --git a/ipc/shm.c b/ipc/shm.c
> index b76be5b..406c5b2 100644
> --- a/ipc/shm.c
> +++ b/ipc/shm.c
> @@ -482,7 +482,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
> /* hugetlb_file_setup applies strict accounting */
> if (shmflg & SHM_NORESERVE)
> acctflag = VM_NORESERVE;
> - file = hugetlb_file_setup(name, size, acctflag,
> + file = hugetlb_file_setup(name, 0, size, acctflag,
> &shp->mlock_user, HUGETLB_SHMFS_INODE);
> } else {
> /*
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 3f758c7..4bf211a 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1099,9 +1099,9 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
> * A dummy user value is used because we are not locking
> * memory so no accounting is necessary
> */
> - len = ALIGN(len, huge_page_size(&default_hstate));
> - file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
> - &user, HUGETLB_ANONHUGE_INODE);
> + file = hugetlb_file_setup(HUGETLB_ANON_FILE, addr, len,
> + VM_NORESERVE, &user,
> + HUGETLB_ANONHUGE_INODE);
> if (IS_ERR(file))
> return PTR_ERR(file);
> }
> --
> 1.7.3.4
>
> --
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