[RESEND RFC PATCH v1 06/20] mm: add new prctl option to get and set ksm for a process
From: Stefan Roesch <hidden>
Date: 2023-01-23 18:04:37
Also in:
linux-doc, linux-fsdevel, linux-kselftest, linux-mm, lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
This adds two new options to the prctl system call - enable ksm for all vmas of a process (if the vmas support it). - query if ksm has been enabled for a process. Signed-off-by: Stefan Roesch <redacted> --- include/uapi/linux/prctl.h | 2 ++ kernel/sys.c | 29 +++++++++++++++++++++++++++++ 2 files changed, 31 insertions(+)
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index a5e06dcbba13..b8ba85f18e43 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h@@ -284,4 +284,6 @@ struct prctl_mm_map { #define PR_SET_VMA 0x53564d41 # define PR_SET_VMA_ANON_NAME 0 +#define PR_SET_MEMORY_MERGE 65 +#define PR_GET_MEMORY_MERGE 66 #endif /* _LINUX_PRCTL_H */
diff --git a/kernel/sys.c b/kernel/sys.c
index 5fd54bf0e886..de218e3b6f42 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c@@ -15,6 +15,7 @@ #include <linux/highuid.h> #include <linux/fs.h> #include <linux/kmod.h> +#include <linux/ksm.h> #include <linux/perf_event.h> #include <linux/resource.h> #include <linux/kernel.h>
@@ -2626,6 +2627,34 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, case PR_SET_VMA: error = prctl_set_vma(arg2, arg3, arg4, arg5); break; +#ifdef CONFIG_KSM + case PR_SET_MEMORY_MERGE: + if (!capable(CAP_SYS_RESOURCE)) + return -EPERM; + + if (arg2) { + if (mmap_write_lock_killable(me->mm)) + return -EINTR; + + if (test_bit(MMF_VM_MERGEABLE, &me->mm->flags)) + error = -EINVAL; + else if (!test_bit(MMF_VM_MERGE_ANY, &me->mm->flags)) + error = __ksm_enter(me->mm, MMF_VM_MERGE_ANY); + mmap_write_unlock(me->mm); + } else { + __ksm_exit(me->mm, MMF_VM_MERGE_ANY); + } + break; + case PR_GET_MEMORY_MERGE: + if (!capable(CAP_SYS_RESOURCE)) + return -EPERM; + + if (arg2 || arg3 || arg4 || arg5) + return -EINVAL; + + error = !!test_bit(MMF_VM_MERGE_ANY, &me->mm->flags); + break; +#endif default: error = -EINVAL; break;
--
2.30.2