From: Christoph Lameter Date: Sun, 8 Jan 2006 09:00:51 +0000 (-0800) Subject: [PATCH] Swap Migration V5: sys_migrate_pages interface X-Git-Tag: v2.6.16-rc1~890 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=39743889aaf76725152f16aa90ca3c45f6d52da3;p=linux-2.6 [PATCH] Swap Migration V5: sys_migrate_pages interface sys_migrate_pages implementation using swap based page migration This is the original API proposed by Ray Bryant in his posts during the first half of 2005 on linux-mm@kvack.org and linux-kernel@vger.kernel.org. The intent of sys_migrate is to migrate memory of a process. A process may have migrated to another node. Memory was allocated optimally for the prior context. sys_migrate_pages allows to shift the memory to the new node. sys_migrate_pages is also useful if the processes available memory nodes have changed through cpuset operations to manually move the processes memory. Paul Jackson is working on an automated mechanism that will allow an automatic migration if the cpuset of a process is changed. However, a user may decide to manually control the migration. This implementation is put into the policy layer since it uses concepts and functions that are also needed for mbind and friends. The patch also provides a do_migrate_pages function that may be useful for cpusets to automatically move memory. sys_migrate_pages does not modify policies in contrast to Ray's implementation. The current code here is based on the swap based page migration capability and thus is not able to preserve the physical layout relative to it containing nodeset (which may be a cpuset). When direct page migration becomes available then the implementation needs to be changed to do a isomorphic move of pages between different nodesets. The current implementation simply evicts all pages in source nodeset that are not in the target nodeset. Patch supports ia64, i386 and x86_64. Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/i386/kernel/syscall_table.S b/arch/i386/kernel/syscall_table.S index f7ba4acc20..6ff3e52432 100644 --- a/arch/i386/kernel/syscall_table.S +++ b/arch/i386/kernel/syscall_table.S @@ -293,3 +293,4 @@ ENTRY(sys_call_table) .long sys_inotify_init .long sys_inotify_add_watch .long sys_inotify_rm_watch + .long sys_migrate_pages diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S index 0741b066b9..7a6ffd6137 100644 --- a/arch/ia64/kernel/entry.S +++ b/arch/ia64/kernel/entry.S @@ -1600,5 +1600,6 @@ sys_call_table: data8 sys_inotify_init data8 sys_inotify_add_watch data8 sys_inotify_rm_watch + data8 sys_migrate_pages // 1280 .org sys_call_table + 8*NR_syscalls // guard against failures to increase NR_syscalls diff --git a/arch/x86_64/ia32/ia32entry.S b/arch/x86_64/ia32/ia32entry.S index df0773c9bd..1f0ff5adc8 100644 --- a/arch/x86_64/ia32/ia32entry.S +++ b/arch/x86_64/ia32/ia32entry.S @@ -643,6 +643,7 @@ ia32_sys_call_table: .quad sys_inotify_init .quad sys_inotify_add_watch .quad sys_inotify_rm_watch + .quad sys_migrate_pages ia32_syscall_end: .rept IA32_NR_syscalls-(ia32_syscall_end-ia32_sys_call_table)/8 .quad ni_syscall diff --git a/include/asm-i386/unistd.h b/include/asm-i386/unistd.h index fe38b9a962..481c3c0ea7 100644 --- a/include/asm-i386/unistd.h +++ b/include/asm-i386/unistd.h @@ -299,8 +299,9 @@ #define __NR_inotify_init 291 #define __NR_inotify_add_watch 292 #define __NR_inotify_rm_watch 293 +#define __NR_migrate_pages 294 -#define NR_syscalls 294 +#define NR_syscalls 295 /* * user-visible error numbers are in the range -1 - -128: see diff --git a/include/asm-ia64/unistd.h b/include/asm-ia64/unistd.h index 2bf543493c..962f9bd1bd 100644 --- a/include/asm-ia64/unistd.h +++ b/include/asm-ia64/unistd.h @@ -269,12 +269,13 @@ #define __NR_inotify_init 1277 #define __NR_inotify_add_watch 1278 #define __NR_inotify_rm_watch 1279 +#define __NR_migrate_pages 1280 #ifdef __KERNEL__ #include -#define NR_syscalls 256 /* length of syscall table */ +#define NR_syscalls 270 /* length of syscall table */ #define __ARCH_WANT_SYS_RT_SIGACTION diff --git a/include/asm-x86_64/ia32_unistd.h b/include/asm-x86_64/ia32_unistd.h index d5166ec386..e8843362a6 100644 --- a/include/asm-x86_64/ia32_unistd.h +++ b/include/asm-x86_64/ia32_unistd.h @@ -299,7 +299,8 @@ #define __NR_ia32_inotify_init 291 #define __NR_ia32_inotify_add_watch 292 #define __NR_ia32_inotify_rm_watch 293 +#define __NR_ia32_migrate_pages 294 -#define IA32_NR_syscalls 294 /* must be > than biggest syscall! */ +#define IA32_NR_syscalls 295 /* must be > than biggest syscall! */ #endif /* _ASM_X86_64_IA32_UNISTD_H_ */ diff --git a/include/asm-x86_64/unistd.h b/include/asm-x86_64/unistd.h index 2c42150bce..e6f896161c 100644 --- a/include/asm-x86_64/unistd.h +++ b/include/asm-x86_64/unistd.h @@ -571,8 +571,10 @@ __SYSCALL(__NR_inotify_init, sys_inotify_init) __SYSCALL(__NR_inotify_add_watch, sys_inotify_add_watch) #define __NR_inotify_rm_watch 255 __SYSCALL(__NR_inotify_rm_watch, sys_inotify_rm_watch) +#define __NR_migrate_pages 256 +__SYSCALL(__NR_migrate_pages, sys_migrate_pages) -#define __NR_syscall_max __NR_inotify_rm_watch +#define __NR_syscall_max __NR_migrate_pages #ifndef __NO_STUBS /* user-visible error numbers are in the range -1 - -4095 */ diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h index 05443a766c..3e61e82968 100644 --- a/include/linux/mempolicy.h +++ b/include/linux/mempolicy.h @@ -162,6 +162,9 @@ static inline void check_highest_zone(int k) policy_zone = k; } +int do_migrate_pages(struct mm_struct *mm, + const nodemask_t *from_nodes, const nodemask_t *to_nodes, int flags); + #else struct mempolicy {}; diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index c7007b1db9..e910d1a481 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -511,5 +511,7 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio); asmlinkage long sys_ioprio_get(int which, int who); asmlinkage long sys_set_mempolicy(int mode, unsigned long __user *nmask, unsigned long maxnode); +asmlinkage long sys_migrate_pages(pid_t pid, unsigned long maxnode, + const unsigned long __user *from, const unsigned long __user *to); #endif diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index 1ab2370e2e..7a8bc7f60d 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -82,6 +82,7 @@ cond_syscall(compat_sys_socketcall); cond_syscall(sys_inotify_init); cond_syscall(sys_inotify_add_watch); cond_syscall(sys_inotify_rm_watch); +cond_syscall(sys_migrate_pages); /* arch-specific weak syscall entries */ cond_syscall(sys_pciconfig_read); diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 9cc6d96283..20d5ad39fa 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -614,12 +614,42 @@ long do_get_mempolicy(int *policy, nodemask_t *nmask, return err; } +/* + * For now migrate_pages simply swaps out the pages from nodes that are in + * the source set but not in the target set. In the future, we would + * want a function that moves pages between the two nodesets in such + * a way as to preserve the physical layout as much as possible. + * + * Returns the number of page that could not be moved. + */ +int do_migrate_pages(struct mm_struct *mm, + const nodemask_t *from_nodes, const nodemask_t *to_nodes, int flags) +{ + LIST_HEAD(pagelist); + int count = 0; + nodemask_t nodes; + + nodes_andnot(nodes, *from_nodes, *to_nodes); + nodes_complement(nodes, nodes); + + down_read(&mm->mmap_sem); + check_range(mm, mm->mmap->vm_start, TASK_SIZE, &nodes, + flags | MPOL_MF_DISCONTIG_OK, &pagelist); + if (!list_empty(&pagelist)) { + migrate_pages(&pagelist, NULL); + if (!list_empty(&pagelist)) + count = putback_lru_pages(&pagelist); + } + up_read(&mm->mmap_sem); + return count; +} + /* * User space interface with variable sized bitmaps for nodelists. */ /* Copy a node mask from user space. */ -static int get_nodes(nodemask_t *nodes, unsigned long __user *nmask, +static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask, unsigned long maxnode) { unsigned long k; @@ -708,6 +738,68 @@ asmlinkage long sys_set_mempolicy(int mode, unsigned long __user *nmask, return do_set_mempolicy(mode, &nodes); } +/* Macro needed until Paul implements this function in kernel/cpusets.c */ +#define cpuset_mems_allowed(task) node_online_map + +asmlinkage long sys_migrate_pages(pid_t pid, unsigned long maxnode, + const unsigned long __user *old_nodes, + const unsigned long __user *new_nodes) +{ + struct mm_struct *mm; + struct task_struct *task; + nodemask_t old; + nodemask_t new; + nodemask_t task_nodes; + int err; + + err = get_nodes(&old, old_nodes, maxnode); + if (err) + return err; + + err = get_nodes(&new, new_nodes, maxnode); + if (err) + return err; + + /* Find the mm_struct */ + read_lock(&tasklist_lock); + task = pid ? find_task_by_pid(pid) : current; + if (!task) { + read_unlock(&tasklist_lock); + return -ESRCH; + } + mm = get_task_mm(task); + read_unlock(&tasklist_lock); + + if (!mm) + return -EINVAL; + + /* + * Check if this process has the right to modify the specified + * process. The right exists if the process has administrative + * capabilities, superuser priviledges or the same + * userid as the target process. + */ + if ((current->euid != task->suid) && (current->euid != task->uid) && + (current->uid != task->suid) && (current->uid != task->uid) && + !capable(CAP_SYS_ADMIN)) { + err = -EPERM; + goto out; + } + + task_nodes = cpuset_mems_allowed(task); + /* Is the user allowed to access the target nodes? */ + if (!nodes_subset(new, task_nodes) && !capable(CAP_SYS_ADMIN)) { + err = -EPERM; + goto out; + } + + err = do_migrate_pages(mm, &old, &new, MPOL_MF_MOVE); +out: + mmput(mm); + return err; +} + + /* Retrieve NUMA policy */ asmlinkage long sys_get_mempolicy(int __user *policy, unsigned long __user *nmask,