[PATCH v3 09/11] mm/mempolicy: add get_mempolicy2 syscall

Gregory Price
2023-12-13T22:41:43Z

get_mempolicy2 is an extensible get_mempolicy interface which allows
a user to retrieve the memory policy for a task or address.

Defined as:

get_mempolicy2(struct mpol_args *args, size_t size,
unsigned long addr, unsigned long flags)

Top level input values:

mpol_args: The field which collects information about the mempolicy
returned to userspace.
addr: if MPOL_F_ADDR is passed in `flags`, this address will be
used to return the mempolicy details of the vma the
address belongs to
flags: if MPOL_F_ADDR, return mempolicy info vma containing addr
else, returns task mempolicy information

Input values include the following fields of mpol_args:

pol_nodes: if set, the nodemask of the policy returned here
pol_maxnodes: if pol_nodes is set, must describe max number of nodes
to be copied to pol_nodes

Output values include the following fields of mpol_args:

mode: mempolicy mode
mode_flags: mempolicy mode flags
home_node: policy home node will be returned here, or -1 if not.
pol_nodes: if set, the nodemask for the mempolicy
policy_node: if the policy has extended node information, it will
be placed here. For example MPOL_INTERLEAVE will
return the next node which will be used for allocation

MPOL_F_NODE has been dropped from get_mempolicy2 (EINVAL).

Suggested-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Gregory Price <gregory.price@memverge.com>
---
.../admin-guide/mm/numa_memory_policy.rst | 10 ++++-
arch/alpha/kernel/syscalls/syscall.tbl | 1 +
arch/arm/tools/syscall.tbl | 1 +
arch/m68k/kernel/syscalls/syscall.tbl | 1 +
arch/microblaze/kernel/syscalls/syscall.tbl | 1 +
arch/mips/kernel/syscalls/syscall_n32.tbl | 1 +
arch/mips/kernel/syscalls/syscall_o32.tbl | 1 +
arch/parisc/kernel/syscalls/syscall.tbl | 1 +
arch/powerpc/kernel/syscalls/syscall.tbl | 1 +
arch/s390/kernel/syscalls/syscall.tbl | 1 +
arch/sh/kernel/syscalls/syscall.tbl | 1 +
arch/sparc/kernel/syscalls/syscall.tbl | 1 +
arch/x86/entry/syscalls/syscall_32.tbl | 1 +
arch/x86/entry/syscalls/syscall_64.tbl | 1 +
arch/xtensa/kernel/syscalls/syscall.tbl | 1 +
include/linux/syscalls.h | 2 +
include/uapi/asm-generic/unistd.h | 4 +-
mm/mempolicy.c | 43 +++++++++++++++++++
18 files changed, 71 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/mm/numa_memory_policy.rst b/Documentation/admin-guide/mm/numa_memory_policy.rst
index e57d400d0281..8c1fcdb30602 100644
--- a/Documentation/admin-guide/mm/numa_memory_policy.rst
+++ b/Documentation/admin-guide/mm/numa_memory_policy.rst
@@ -456,11 +456,19 @@ Get [Task] Memory Policy or Related Information::
long get_mempolicy(int *mode,
const unsigned long *nmask, unsigned long maxnode,
void *addr, int flags);
+ long get_mempolicy2(struct mpol_args args, size_t size,
+ unsigned long addr, unsigned long flags);

Queries the "task/process memory policy" of the calling task, or the
policy or location of a specified virtual address, depending on the
'flags' argument.

+get_mempolicy2() is an extended version of get_mempolicy() capable of
+acquiring extended information about a mempolicy, including those
+that can only be set via set_mempolicy2() or mbind2().
+
+MPOL_F_NODE functionality has been removed from get_mempolicy2().
+
See the get_mempolicy(2) man page for more details

@@ -504,7 +512,7 @@ Extended Mempolicy Arguments::
The extended mempolicy argument structure is defined to allow the mempolicy
interfaces future extensibility without the need for additional system calls.

-Extended interfaces (set_mempolicy2) use this argument structure.
+Extended interfaces (set_mempolicy2 and get_mempolicy2) use this structure.

The core arguments (mode, mode_flags, pol_nodes, and pol_maxnodes) apply to
all interfaces relative to their non-extended counterparts. Each additional
diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl
index 0dc288a1118a..0301a8b0a262 100644
--- a/arch/alpha/kernel/syscalls/syscall.tbl
+++ b/arch/alpha/kernel/syscalls/syscall.tbl
@@ -497,3 +497,4 @@
565 common futex_wait sys_futex_wait
566 common futex_requeue sys_futex_requeue
567 common set_mempolicy2 sys_set_mempolicy2
+568 common get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
index 50172ec0e1f5..771a33446e8e 100644
--- a/arch/arm/tools/syscall.tbl
+++ b/arch/arm/tools/syscall.tbl
@@ -471,3 +471,4 @@
455 common futex_wait sys_futex_wait
456 common futex_requeue sys_futex_requeue
457 common set_mempolicy2 sys_set_mempolicy2
+458 common get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl
index 839d90c535f2..048a409e684c 100644
--- a/arch/m68k/kernel/syscalls/syscall.tbl
+++ b/arch/m68k/kernel/syscalls/syscall.tbl
@@ -457,3 +457,4 @@
455 common futex_wait sys_futex_wait
456 common futex_requeue sys_futex_requeue
457 common set_mempolicy2 sys_set_mempolicy2
+458 common get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl
index 567c8b883735..327b01bd6793 100644
--- a/arch/microblaze/kernel/syscalls/syscall.tbl
+++ b/arch/microblaze/kernel/syscalls/syscall.tbl
@@ -463,3 +463,4 @@
455 common futex_wait sys_futex_wait
456 common futex_requeue sys_futex_requeue
457 common set_mempolicy2 sys_set_mempolicy2
+458 common get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl
index cc0640e16f2f..921d58e1da23 100644
--- a/arch/mips/kernel/syscalls/syscall_n32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n32.tbl
@@ -396,3 +396,4 @@
455 n32 futex_wait sys_futex_wait
456 n32 futex_requeue sys_futex_requeue
457 n32 set_mempolicy2 sys_set_mempolicy2
+458 n32 get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
index f7262fde98d9..9271c83c9993 100644
--- a/arch/mips/kernel/syscalls/syscall_o32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
@@ -445,3 +445,4 @@
455 o32 futex_wait sys_futex_wait
456 o32 futex_requeue sys_futex_requeue
457 o32 set_mempolicy2 sys_set_mempolicy2
+458 o32 get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
index e10f0e8bd064..0654f3f89fc7 100644
--- a/arch/parisc/kernel/syscalls/syscall.tbl
+++ b/arch/parisc/kernel/syscalls/syscall.tbl
@@ -456,3 +456,4 @@
455 common futex_wait sys_futex_wait
456 common futex_requeue sys_futex_requeue
457 common set_mempolicy2 sys_set_mempolicy2
+458 common get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
index 4f03f5f42b78..ac11d2064e7a 100644
--- a/arch/powerpc/kernel/syscalls/syscall.tbl
+++ b/arch/powerpc/kernel/syscalls/syscall.tbl
@@ -544,3 +544,4 @@
455 common futex_wait sys_futex_wait
456 common futex_requeue sys_futex_requeue
457 common set_mempolicy2 sys_set_mempolicy2
+458 common get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
index f98dadc2e9df..1cdcafe1ccca 100644
--- a/arch/s390/kernel/syscalls/syscall.tbl
+++ b/arch/s390/kernel/syscalls/syscall.tbl
@@ -460,3 +460,4 @@
455 common futex_wait sys_futex_wait sys_futex_wait
456 common futex_requeue sys_futex_requeue sys_futex_requeue
457 common set_mempolicy2 sys_set_mempolicy2 sys_set_mempolicy2
+458 common get_mempolicy2 sys_get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl
index f47ba9f2d05d..f71742024c29 100644
--- a/arch/sh/kernel/syscalls/syscall.tbl
+++ b/arch/sh/kernel/syscalls/syscall.tbl
@@ -460,3 +460,4 @@
455 common futex_wait sys_futex_wait
456 common futex_requeue sys_futex_requeue
457 common set_mempolicy2 sys_set_mempolicy2
+458 common get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl
index 53fb16616728..2fbf5dbe0620 100644
--- a/arch/sparc/kernel/syscalls/syscall.tbl
+++ b/arch/sparc/kernel/syscalls/syscall.tbl
@@ -503,3 +503,4 @@
455 common futex_wait sys_futex_wait
456 common futex_requeue sys_futex_requeue
457 common set_mempolicy2 sys_set_mempolicy2
+458 common get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 4b4dc41b24ee..0af813b9a118 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -462,3 +462,4 @@
455 i386 futex_wait sys_futex_wait
456 i386 futex_requeue sys_futex_requeue
457 i386 set_mempolicy2 sys_set_mempolicy2
+458 i386 get_mempolicy2 sys_get_mempolicy2
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 1bc2190bec27..0b777876fc15 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -379,6 +379,7 @@
455 common futex_wait sys_futex_wait
456 common futex_requeue sys_futex_requeue
457 common set_mempolicy2 sys_set_mempolicy2
+458 common get_mempolicy2 sys_get_mempolicy2

#
# Due to a historical design error, certain syscalls are numbered differently
diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl
index e26dc89399eb..4536c9a4227d 100644
--- a/arch/xtensa/kernel/syscalls/syscall.tbl
+++ b/arch/xtensa/kernel/syscalls/syscall.tbl
@@ -428,3 +428,4 @@
455 common futex_wait sys_futex_wait
456 common futex_requeue sys_futex_requeue
457 common set_mempolicy2 sys_set_mempolicy2
+458 common get_mempolicy2 sys_get_mempolicy2
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 451f0089601f..f696855cbe8c 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -821,6 +821,8 @@ asmlinkage long sys_get_mempolicy(int __user *policy,
unsigned long __user *nmask,
unsigned long maxnode,
unsigned long addr, unsigned long flags);
+asmlinkage long sys_get_mempolicy2(struct mpol_args __user *args, size_t size,
+ unsigned long addr, unsigned long flags);
asmlinkage long sys_set_mempolicy(int mode, const unsigned long __user *nmask,
unsigned long maxnode);
asmlinkage long sys_set_mempolicy2(struct mpol_args __user *args, size_t size,
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 55486aba099f..719accc731db 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -830,9 +830,11 @@ __SYSCALL(__NR_futex_wait, sys_futex_wait)
__SYSCALL(__NR_futex_requeue, sys_futex_requeue)
#define __NR_set_mempolicy2 457
__SYSCALL(__NR_set_mempolicy2, sys_set_mempolicy2)
+#define __NR_get_mempolicy2 458
+__SYSCALL(__NR_get_mempolicy2, sys_get_mempolicy2)

#undef __NR_syscalls
-#define __NR_syscalls 458
+#define __NR_syscalls 459

/*
* 32 bit systems traditionally used different
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 4bf563f3732b..09c613113c7c 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1863,6 +1863,49 @@ SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
return kernel_get_mempolicy(policy, nmask, maxnode, addr, flags);
}

+SYSCALL_DEFINE4(get_mempolicy2, struct mpol_args __user *, uargs, size_t, usize,
+ unsigned long, addr, unsigned long, flags)
+{
+ struct mpol_args kargs;
+ struct mempolicy_args margs;
+ int err;
+ nodemask_t policy_nodemask;
+ unsigned long __user *nodes_ptr;
+
+ if (flags & ~(MPOL_F_ADDR))
+ return -EINVAL;
+
+ /* initialize any memory liable to be copied to userland */
+ memset(&margs, 0, sizeof(margs));
+
+ err = copy_struct_from_user(&kargs, sizeof(kargs), uargs, usize);
+ if (err)
+ return -EINVAL;
+
+ margs.policy_nodes = kargs.pol_nodes ? &policy_nodemask : NULL;
+ if (flags & MPOL_F_ADDR)
+ err = do_get_vma_mempolicy(untagged_addr(addr), NULL, &margs);
+ else
+ err = do_get_task_mempolicy(&margs);
+
+ if (err)
+ return err;
+
+ kargs.mode = margs.mode;
+ kargs.mode_flags = margs.mode_flags;
+ kargs.policy_node = margs.policy_node;
+ kargs.home_node = margs.home_node;
+ if (kargs.pol_nodes) {
+ nodes_ptr = u64_to_user_ptr(kargs.pol_nodes);
+ err = copy_nodes_to_user(nodes_ptr, kargs.pol_maxnodes,
+ margs.policy_nodes);
+ if (err)
+ return err;
+ }
+
+ return copy_to_user(uargs, &kargs, usize) ? -EFAULT : 0;
+}
+
bool vma_migratable(struct vm_area_struct *vma)
{
if (vma->vm_flags & (VM_IO | VM_PFNMAP))
--
2.39.1