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Message-ID: <20130104042520.GC2617@blaptop>
Date: Fri, 4 Jan 2013 13:25:20 +0900
From: Minchan Kim <minchan@...nel.org>
To: Taras Glek <tglek@...illa.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
Michael Kerrisk <mtk.manpages@...il.com>,
Arun Sharma <asharma@...com>, sanjay@...gle.com,
Paul Turner <pjt@...gle.com>,
David Rientjes <rientjes@...gle.com>,
John Stultz <john.stultz@...aro.org>,
Christoph Lameter <cl@...ux.com>,
Android Kernel Team <kernel-team@...roid.com>,
Robert Love <rlove@...gle.com>, Mel Gorman <mel@....ul.ie>,
Hugh Dickins <hughd@...gle.com>,
Dave Hansen <dave@...ux.vnet.ibm.com>,
Rik van Riel <riel@...hat.com>,
Dave Chinner <david@...morbit.com>, Neil Brown <neilb@...e.de>,
Mike Hommey <mh@...ndium.org>,
KOSAKI Motohiro <kosaki.motohiro@...il.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [RFC 1/8] Introduce new system call mvolatile
Hi,
On Thu, Jan 03, 2013 at 10:35:24AM -0800, Taras Glek wrote:
> On 1/2/2013 8:27 PM, Minchan Kim wrote:
> >This patch adds new system call m[no]volatile.
> >If someone asks is_volatile system call, it could be added, too.
> >
> >The reason why I introduced new system call instead of madvise is
> >m[no]volatile vma handling is totally different with madvise's vma
> >handling.
> >
> >1) The m[no]volatile should be successful although the range includes
> > unmapped or non-volatile range. It just skips such range
> > without stopping with returning error although it encounters
> > invalid range. It makes user convenient without calling several
> > system call of small range - Suggested by John Stultz
> >
> >2) The purged state of volatile range should be propagated out to user
> > although the range is merged with adjacent non-volatile range when
> > user calls mnovolatile.
> >
> >3) mvolatile's interface could be changed with madvise
> > in future discussion. For example, I feel needs
> > movlatile(start, len, mode).
> > 'mode' means FULL_VOLATILE or PARTIAL_VOLATILE.
> > FULL volatile means that if VM decide to reclaim the range, it would
> > reclaim all of pages in the range but in case of PARTIAL_VOLATILE,
> > VM could reclaim just a few number of pages in the range.
> > In case of tmpfs-volatile, user may regenerate all images data once
> > one of page in the range is discarded so there is pointless that
> > VM discard a page in the range when memory pressure is severe.
> > In case of anon-volatile, too excess discarding cause too many minor
> > fault for the allocator so it would be better to discard part of
> > the range.
> I don't understand point 3).
> Are you saying that using mvolatile in conjuction with madvise could
> allow mvolatile behavior to be tweaked in the future? Or are you
> suggesting adding an extra parameter in the future(what would that
> have to do with madvise)?
I meant I might want to expand mvolatile's interface like below
during discussion.
int mvolatile(start, len, mode);
>
> 4) Having a new system call makes it easier for userspace apps to
> detect kernels without this functionality.
I coudn't understand your claim.
Now mvolatile just return EINVAL on !CONFIG_VOLATILE_PAGE system.
Why is it easy compared to returning EINVAL when we call madvise(VOLATILE)
on !CONFIG_VOLATILE_PAGE?
>
> I really like the proposed interface. I like the suggestion of
Thanks.
> having explicit FULL|PARTIAL_VOLATILE. Why not include
> PARTIAL_VOLATILE as a required 3rd param in first version with
> expectation that FULL_VOLATILE will be added later(and returning
> some not-supported error in meantime)?
I just wanted to discuss about needs of it.
The reason I need PARTIAL_VOLATILE is that avoids many minor fault
for allocator. Is it useful for tmpfs-volatile, too?
Thanks for the feedback, Taras.
> >
> >3) The mvolatile system call's return value is quite different with
> > madvise. Look at below semantic explanation.
> >
> >So I want to separate mvolatile from madvise.
> >
> >mvolatile(start, len)'s semantics
> >
> >1) It makes range(start, len) as volatile although the range includes
> >unmapped area, speacial mapping and mlocked area which are just skipped.
> >
> >Return -EINVAL if range doesn't include a right vma at all.
> >Return -ENOMEM with interrupting range opeartion if memory is not
> >enough to merge/split vmas. In this case, some ranges would be
> >volatile and others not so user may recall mvolatile after he
> >cancel all range by mnovolatile.
> >Return 0 if range consists of only proper vmas.
> >Return 1 if part of range includes hole/huge/ksm/mlock/special area.
> >
> >2) If user calls mvolatile to the range which was already volatile VMA and
> >even purged state, VOLATILE attributes still remains but purged state
> >is reset. I expect some user want to split volatile vma into smaller
> >ranges. Although he can do it for mnovlatile(whole range) and serveral calling
> >with movlatile(smaller range), this function can avoid mnovolatile if he
> >doesn't care purged state. I'm not sure we really need this function so
> >I hope listen opinions. Unfortunately, current implemenation doesn't split
> >volatile VMA with new range in this case. I forgot implementing it
> >in this version but decide to send it to listen opinions because
> >implementing is rather trivial if we decided.
> >
> >mnovolatile(start, len)'s semantics is following as.
> >
> >1) It makes range(start, len) as non-volatile although the range
> >includes unmapped area, speacial mapping and non-volatile range
> >which are just skipped.
> >
> >2) If the range is purged, it will return 1 regardless of including
> >invalid range.
> If I understand this correctly:
> mvolatile(0, 10);
> //then range [9,10] is purged by kernel
> mnovolatile(0,4) will fail?
> that seems counterintuitive.
>
> One of the uses for mnovolatile is to atomicly lock the pages(vs a
> racy proposed is_volatile) syscall. Above situation would make it
> less effective.
>
>
> >
> >3) It returns -ENOMEM if system doesn't have enough memory for vma operation.
> >
> >4) It returns -EINVAL if range doesn't include a right vma at all.
> >
> >5) If user try to access purged range without mnovoatile call, it encounters
> >SIGBUS which would show up next patch.
> >
> >Cc: Michael Kerrisk <mtk.manpages@...il.com>
> >Cc: Arun Sharma <asharma@...com>
> >Cc: sanjay@...gle.com
> >Cc: Paul Turner <pjt@...gle.com>
> >CC: David Rientjes <rientjes@...gle.com>
> >Cc: John Stultz <john.stultz@...aro.org>
> >Cc: Andrew Morton <akpm@...ux-foundation.org>
> >Cc: Christoph Lameter <cl@...ux.com>
> >Cc: Android Kernel Team <kernel-team@...roid.com>
> >Cc: Robert Love <rlove@...gle.com>
> >Cc: Mel Gorman <mel@....ul.ie>
> >Cc: Hugh Dickins <hughd@...gle.com>
> >Cc: Dave Hansen <dave@...ux.vnet.ibm.com>
> >Cc: Rik van Riel <riel@...hat.com>
> >Cc: Dave Chinner <david@...morbit.com>
> >Cc: Neil Brown <neilb@...e.de>
> >Cc: Mike Hommey <mh@...ndium.org>
> >Cc: Taras Glek <tglek@...illa.com>
> >Cc: KOSAKI Motohiro <kosaki.motohiro@...il.com>
> >Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> >Signed-off-by: Minchan Kim <minchan@...nel.org>
> >---
> > arch/x86/syscalls/syscall_64.tbl | 2 +
> > fs/exec.c | 4 +-
> > include/linux/mm.h | 6 +-
> > include/linux/mm_types.h | 4 +
> > include/linux/mvolatile.h | 30 ++++
> > include/linux/syscalls.h | 2 +
> > mm/Kconfig | 11 ++
> > mm/Makefile | 2 +-
> > mm/madvise.c | 2 +-
> > mm/mempolicy.c | 2 +-
> > mm/mlock.c | 7 +-
> > mm/mmap.c | 62 ++++++--
> > mm/mprotect.c | 3 +-
> > mm/mremap.c | 2 +-
> > mm/mvolatile.c | 312 ++++++++++++++++++++++++++++++++++++++
> > mm/rmap.c | 2 +
> > 16 files changed, 427 insertions(+), 26 deletions(-)
> > create mode 100644 include/linux/mvolatile.h
> > create mode 100644 mm/mvolatile.c
> >
> >diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl
> >index a582bfe..568d488 100644
> >--- a/arch/x86/syscalls/syscall_64.tbl
> >+++ b/arch/x86/syscalls/syscall_64.tbl
> >@@ -319,6 +319,8 @@
> > 310 64 process_vm_readv sys_process_vm_readv
> > 311 64 process_vm_writev sys_process_vm_writev
> > 312 common kcmp sys_kcmp
> >+313 common mvolatile sys_mvolatile
> >+314 common mnovolatile sys_mnovolatile
> > #
> > # x32-specific system call numbers start at 512 to avoid cache impact
> >diff --git a/fs/exec.c b/fs/exec.c
> >index 0039055..da677d1 100644
> >--- a/fs/exec.c
> >+++ b/fs/exec.c
> >@@ -594,7 +594,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
> > /*
> > * cover the whole range: [new_start, old_end)
> > */
> >- if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
> >+ if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL, NULL))
> > return -ENOMEM;
> > /*
> >@@ -628,7 +628,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
> > /*
> > * Shrink the vma to just the new range. Always succeeds.
> > */
> >- vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
> >+ vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL, NULL);
> > return 0;
> > }
> >diff --git a/include/linux/mm.h b/include/linux/mm.h
> >index bcaab4e..4bb59f3 100644
> >--- a/include/linux/mm.h
> >+++ b/include/linux/mm.h
> >@@ -87,6 +87,7 @@ extern unsigned int kobjsize(const void *objp);
> > #define VM_PFNMAP 0x00000400 /* Page-ranges managed without "struct page", just pure PFN */
> > #define VM_DENYWRITE 0x00000800 /* ETXTBSY on write attempts.. */
> >+#define VM_VOLATILE 0x00001000 /* Pages could be discarede without swapout */
> > #define VM_LOCKED 0x00002000
> > #define VM_IO 0x00004000 /* Memory mapped I/O or similar */
> >@@ -1411,11 +1412,12 @@ void anon_vma_interval_tree_verify(struct anon_vma_chain *node);
> > /* mmap.c */
> > extern int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin);
> > extern int vma_adjust(struct vm_area_struct *vma, unsigned long start,
> >- unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert);
> >+ unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
> >+ bool *purged);
> > extern struct vm_area_struct *vma_merge(struct mm_struct *,
> > struct vm_area_struct *prev, unsigned long addr, unsigned long end,
> > unsigned long vm_flags, struct anon_vma *, struct file *, pgoff_t,
> >- struct mempolicy *);
> >+ struct mempolicy *, bool *purged);
> > extern struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *);
> > extern int split_vma(struct mm_struct *,
> > struct vm_area_struct *, unsigned long addr, int new_below);
> >diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> >index 31f8a3a..1eaf458 100644
> >--- a/include/linux/mm_types.h
> >+++ b/include/linux/mm_types.h
> >@@ -275,6 +275,10 @@ struct vm_area_struct {
> > #ifdef CONFIG_NUMA
> > struct mempolicy *vm_policy; /* NUMA policy for the VMA */
> > #endif
> >+#ifdef CONFIG_VOLATILE_PAGE
> >+ /* True if more than a page in this vma is reclaimed. */
> >+ bool purged; /* Serialized by mmap_sem and anon_vma's mutex */
> >+#endif
> > };
> > struct core_thread {
> >diff --git a/include/linux/mvolatile.h b/include/linux/mvolatile.h
> >new file mode 100644
> >index 0000000..cfb12b4
> >--- /dev/null
> >+++ b/include/linux/mvolatile.h
> >@@ -0,0 +1,30 @@
> >+#ifndef __LINUX_MVOLATILE_H
> >+#define __LINUX_MVOLATILE_H
> >+
> >+#include <linux/syscalls.h>
> >+
> >+#ifdef CONFIG_VOLATILE_PAGE
> >+static inline bool vma_purged(struct vm_area_struct *vma)
> >+{
> >+ return vma->purged;
> >+}
> >+
> >+static inline void vma_purge_copy(struct vm_area_struct *dst,
> >+ struct vm_area_struct *src)
> >+{
> >+ dst->purged = src->purged;
> >+}
> >+#else
> >+static inline bool vma_purged(struct vm_area_struct *vma)
> >+{
> >+ return false;
> >+}
> >+
> >+static inline void vma_purge_copy(struct vm_area_struct *dst,
> >+ struct vm_area_struct *src)
> >+{
> >+
> >+}
> >+#endif
> >+#endif
> >+
> >diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> >index 727f0cd..a8ded1c 100644
> >--- a/include/linux/syscalls.h
> >+++ b/include/linux/syscalls.h
> >@@ -470,6 +470,8 @@ asmlinkage long sys_munlock(unsigned long start, size_t len);
> > asmlinkage long sys_mlockall(int flags);
> > asmlinkage long sys_munlockall(void);
> > asmlinkage long sys_madvise(unsigned long start, size_t len, int behavior);
> >+asmlinkage long sys_mvolatile(unsigned long start, size_t len);
> >+asmlinkage long sys_mnovolatile(unsigned long start, size_t len);
> > asmlinkage long sys_mincore(unsigned long start, size_t len,
> > unsigned char __user * vec);
> >diff --git a/mm/Kconfig b/mm/Kconfig
> >index a3f8ddd..30b24ba 100644
> >--- a/mm/Kconfig
> >+++ b/mm/Kconfig
> >@@ -355,6 +355,17 @@ choice
> > benefit.
> > endchoice
> >+config VOLATILE_PAGE
> >+ bool "Volatile Page Support"
> >+ depends on MMU
> >+ help
> >+ Enabling this option adds the system calls mvolatile and mnovolatile
> >+ which are for giving user's address space range to kernel so VM
> >+ can discard pages of the range anytime instead swapout. This feature
> >+ can enhance performance to certain application(ex, memory allocator,
> >+ web browser's tmpfs pages) by reduce the number of minor fault and
> >+ swap out.
> >+
> > config CROSS_MEMORY_ATTACH
> > bool "Cross Memory Support"
> > depends on MMU
> >diff --git a/mm/Makefile b/mm/Makefile
> >index 6b025f8..1efb735 100644
> >--- a/mm/Makefile
> >+++ b/mm/Makefile
> >@@ -5,7 +5,7 @@
> > mmu-y := nommu.o
> > mmu-$(CONFIG_MMU) := fremap.o highmem.o madvise.o memory.o mincore.o \
> > mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \
> >- vmalloc.o pagewalk.o pgtable-generic.o
> >+ mvolatile.o vmalloc.o pagewalk.o pgtable-generic.o
> > ifdef CONFIG_CROSS_MEMORY_ATTACH
> > mmu-$(CONFIG_MMU) += process_vm_access.o
> >diff --git a/mm/madvise.c b/mm/madvise.c
> >index 03dfa5c..6ffad21 100644
> >--- a/mm/madvise.c
> >+++ b/mm/madvise.c
> >@@ -99,7 +99,7 @@ static long madvise_behavior(struct vm_area_struct * vma,
> > pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
> > *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
> >- vma->vm_file, pgoff, vma_policy(vma));
> >+ vma->vm_file, pgoff, vma_policy(vma), NULL);
> > if (*prev) {
> > vma = *prev;
> > goto success;
> >diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> >index 4ea600d..9b1aa2d 100644
> >--- a/mm/mempolicy.c
> >+++ b/mm/mempolicy.c
> >@@ -675,7 +675,7 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
> > ((vmstart - vma->vm_start) >> PAGE_SHIFT);
> > prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
> > vma->anon_vma, vma->vm_file, pgoff,
> >- new_pol);
> >+ new_pol, NULL);
> > if (prev) {
> > vma = prev;
> > next = vma->vm_next;
> >diff --git a/mm/mlock.c b/mm/mlock.c
> >index f0b9ce5..e03523a 100644
> >--- a/mm/mlock.c
> >+++ b/mm/mlock.c
> >@@ -316,13 +316,14 @@ static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
> > int ret = 0;
> > int lock = !!(newflags & VM_LOCKED);
> >- if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) ||
> >- is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm))
> >+ if (newflags == vma->vm_flags || (vma->vm_flags &
> >+ (VM_SPECIAL|VM_VOLATILE)) || is_vm_hugetlb_page(vma) ||
> >+ vma == get_gate_vma(current->mm))
> > goto out; /* don't set VM_LOCKED, don't count */
> > pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
> > *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
> >- vma->vm_file, pgoff, vma_policy(vma));
> >+ vma->vm_file, pgoff, vma_policy(vma), NULL);
> > if (*prev) {
> > vma = *prev;
> > goto success;
> >diff --git a/mm/mmap.c b/mm/mmap.c
> >index 9a796c4..ba636c3 100644
> >--- a/mm/mmap.c
> >+++ b/mm/mmap.c
> >@@ -31,6 +31,7 @@
> > #include <linux/audit.h>
> > #include <linux/khugepaged.h>
> > #include <linux/uprobes.h>
> >+#include <linux/mvolatile.h>
> > #include <asm/uaccess.h>
> > #include <asm/cacheflush.h>
> >@@ -516,7 +517,8 @@ __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
> > * before we drop the necessary locks.
> > */
> > int vma_adjust(struct vm_area_struct *vma, unsigned long start,
> >- unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
> >+ unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
> >+ bool *purged)
> > {
> > struct mm_struct *mm = vma->vm_mm;
> > struct vm_area_struct *next = vma->vm_next;
> >@@ -527,10 +529,9 @@ int vma_adjust(struct vm_area_struct *vma, unsigned long start,
> > struct file *file = vma->vm_file;
> > long adjust_next = 0;
> > int remove_next = 0;
> >+ struct vm_area_struct *exporter = NULL;
> > if (next && !insert) {
> >- struct vm_area_struct *exporter = NULL;
> >-
> > if (end >= next->vm_end) {
> > /*
> > * vma expands, overlapping all the next, and
> >@@ -621,6 +622,15 @@ again: remove_next = 1 + (end > next->vm_end);
> > if (adjust_next) {
> > next->vm_start += adjust_next << PAGE_SHIFT;
> > next->vm_pgoff += adjust_next;
> >+ /*
> >+ * Look at mm/mvolatile.c for knowing terminology.
> >+ * V4. NNPPVV -> NNNPVV
> >+ */
> >+ if (purged) {
> >+ *purged = vma_purged(next);
> >+ if (exporter == vma) /* V5. VVPPNN -> VVPNNN */
> >+ *purged = vma_purged(vma);
> >+ }
> > }
> > if (root) {
> >@@ -651,6 +661,13 @@ again: remove_next = 1 + (end > next->vm_end);
> > anon_vma_interval_tree_post_update_vma(vma);
> > if (adjust_next)
> > anon_vma_interval_tree_post_update_vma(next);
> >+ /*
> >+ * Look at mm/mvolatile.c for knowing terminology.
> >+ * V7. VVPPVV -> VVNPVV
> >+ * V8. VVPPVV -> VVPNVV
> >+ */
> >+ if (insert)
> >+ vma_purge_copy(insert, vma);
> > anon_vma_unlock(anon_vma);
> > }
> > if (mapping)
> >@@ -670,6 +687,20 @@ again: remove_next = 1 + (end > next->vm_end);
> > }
> > if (next->anon_vma)
> > anon_vma_merge(vma, next);
> >+
> >+ /*
> >+ * next is detatched from anon vma chain so purged isn't
> >+ * raced any more.
> >+ * Look at mm/mvolatile.c for knowing terminology.
> >+ *
> >+ * V1. NNPPVV -> NNNNVV
> >+ * V2. VVPPNN -> VVNNNN
> >+ * V3. NNPPNN -> NNNNNN
> >+ */
> >+ if (purged) {
> >+ *purged |= vma_purged(vma); /* case V2 */
> >+ *purged |= vma_purged(next); /* case V1,V3 */
> >+ }
> > mm->map_count--;
> > mpol_put(vma_policy(next));
> > kmem_cache_free(vm_area_cachep, next);
> >@@ -798,7 +829,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
> > struct vm_area_struct *prev, unsigned long addr,
> > unsigned long end, unsigned long vm_flags,
> > struct anon_vma *anon_vma, struct file *file,
> >- pgoff_t pgoff, struct mempolicy *policy)
> >+ pgoff_t pgoff, struct mempolicy *policy, bool *purged)
> > {
> > pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
> > struct vm_area_struct *area, *next;
> >@@ -808,7 +839,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
> > * We later require that vma->vm_flags == vm_flags,
> > * so this tests vma->vm_flags & VM_SPECIAL, too.
> > */
> >- if (vm_flags & VM_SPECIAL)
> >+ if (vm_flags & (VM_SPECIAL|VM_VOLATILE))
> > return NULL;
> > if (prev)
> >@@ -837,10 +868,10 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
> > next->anon_vma, NULL)) {
> > /* cases 1, 6 */
> > err = vma_adjust(prev, prev->vm_start,
> >- next->vm_end, prev->vm_pgoff, NULL);
> >+ next->vm_end, prev->vm_pgoff, NULL, purged);
> > } else /* cases 2, 5, 7 */
> > err = vma_adjust(prev, prev->vm_start,
> >- end, prev->vm_pgoff, NULL);
> >+ end, prev->vm_pgoff, NULL, purged);
> > if (err)
> > return NULL;
> > khugepaged_enter_vma_merge(prev);
> >@@ -856,10 +887,10 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
> > anon_vma, file, pgoff+pglen)) {
> > if (prev && addr < prev->vm_end) /* case 4 */
> > err = vma_adjust(prev, prev->vm_start,
> >- addr, prev->vm_pgoff, NULL);
> >+ addr, prev->vm_pgoff, NULL, purged);
> > else /* cases 3, 8 */
> > err = vma_adjust(area, addr, next->vm_end,
> >- next->vm_pgoff - pglen, NULL);
> >+ next->vm_pgoff - pglen, NULL, purged);
> > if (err)
> > return NULL;
> > khugepaged_enter_vma_merge(area);
> >@@ -1292,7 +1323,8 @@ munmap_back:
> > /*
> > * Can we just expand an old mapping?
> > */
> >- vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
> >+ vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file,
> >+ pgoff, NULL, NULL);
> > if (vma)
> > goto out;
> >@@ -2025,9 +2057,10 @@ static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
> > if (new_below)
> > err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
> >- ((addr - new->vm_start) >> PAGE_SHIFT), new);
> >+ ((addr - new->vm_start) >> PAGE_SHIFT), new, NULL);
> > else
> >- err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
> >+ err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff,
> >+ new, NULL);
> > /* Success. */
> > if (!err)
> >@@ -2240,7 +2273,7 @@ static unsigned long do_brk(unsigned long addr, unsigned long len)
> > /* Can we just expand an old private anonymous mapping? */
> > vma = vma_merge(mm, prev, addr, addr + len, flags,
> >- NULL, NULL, pgoff, NULL);
> >+ NULL, NULL, pgoff, NULL, NULL);
> > if (vma)
> > goto out;
> >@@ -2396,7 +2429,8 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
> > if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
> > return NULL; /* should never get here */
> > new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
> >- vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
> >+ vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
> >+ NULL);
> > if (new_vma) {
> > /*
> > * Source vma may have been merged into new_vma
> >diff --git a/mm/mprotect.c b/mm/mprotect.c
> >index a409926..f461177 100644
> >--- a/mm/mprotect.c
> >+++ b/mm/mprotect.c
> >@@ -179,7 +179,8 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
> > */
> > pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
> > *pprev = vma_merge(mm, *pprev, start, end, newflags,
> >- vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
> >+ vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
> >+ NULL);
> > if (*pprev) {
> > vma = *pprev;
> > goto success;
> >diff --git a/mm/mremap.c b/mm/mremap.c
> >index 1b61c2d..8586c52 100644
> >--- a/mm/mremap.c
> >+++ b/mm/mremap.c
> >@@ -512,7 +512,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
> > int pages = (new_len - old_len) >> PAGE_SHIFT;
> > if (vma_adjust(vma, vma->vm_start, addr + new_len,
> >- vma->vm_pgoff, NULL)) {
> >+ vma->vm_pgoff, NULL, NULL)) {
> > ret = -ENOMEM;
> > goto out;
> > }
> >diff --git a/mm/mvolatile.c b/mm/mvolatile.c
> >new file mode 100644
> >index 0000000..8b812d2
> >--- /dev/null
> >+++ b/mm/mvolatile.c
> >@@ -0,0 +1,312 @@
> >+/*
> >+ * linux/mm/mvolatile.c
> >+ *
> >+ * Copyright 2012 Minchan Kim
> >+ *
> >+ * This work is licensed under the terms of the GNU GPL, version 2. See
> >+ * the COPYING file in the top-level directory.
> >+ */
> >+
> >+#include <linux/mvolatile.h>
> >+#include <linux/mm_types.h>
> >+#include <linux/mm.h>
> >+#include <linux/rmap.h>
> >+#include <linux/mempolicy.h>
> >+
> >+#ifndef CONFIG_VOLATILE_PAGE
> >+SYSCALL_DEFINE2(mnovolatile, unsigned long, start, size_t, len)
> >+{
> >+ return -EINVAL;
> >+}
> >+
> >+SYSCALL_DEFINE2(mvolatile, unsigned long, start, size_t, len)
> >+{
> >+ return -EINVAL;
> >+}
> >+#else
> >+
> >+#define NO_PURGED 0
> >+#define PURGED 1
> >+
> >+/*
> >+ * N: Normal VMA
> >+ * V: Volatile VMA
> >+ * P: Purged volatile VMA
> >+ *
> >+ * Assume that each VMA has two block so case 1-8 consists of three VMA.
> >+ * For example, NNPPVV means VMA1 has normal VMA, VMA2 has purged volailte VMA,
> >+ * and VMA3 has volatile VMA. With another example, NNPVVV means VMA1 has
> >+ * normal VMA, VMA2-1 has purged volatile VMA, VMA2-2 has volatile VMA.
> >+ *
> >+ * Case 7,8 create a new VMA and we call it VMA4 which can be loated before VMA2
> >+ * or after.
> >+ *
> >+ * Notice: The merge between volatile VMAs shouldn't happen.
> >+ * If we call mnovolatile(VMA2),
> >+ *
> >+ * Case 1 NNPPVV -> NNNNVV
> >+ * Case 2 VVPPNN -> VVNNNN
> >+ * Case 3 NNPPNN -> NNNNNN
> >+ * Case 4 NNPPVV -> NNNPVV
> >+ * case 5 VVPPNN -> VVPNNN
> >+ * case 6 VVPPVV -> VVNNVV
> >+ * case 7 VVPPVV -> VVNPVV
> >+ * case 8 VVPPVV -> VVPNVV
> >+ */
> >+static int do_mnovolatile(struct vm_area_struct *vma,
> >+ struct vm_area_struct **prev, unsigned long start,
> >+ unsigned long end, bool *is_purged)
> >+{
> >+ unsigned long new_flags;
> >+ int error = 0;
> >+ struct mm_struct *mm = vma->vm_mm;
> >+ pgoff_t pgoff;
> >+ bool purged = false;
> >+
> >+ new_flags = vma->vm_flags & ~VM_VOLATILE;
> >+ if (new_flags == vma->vm_flags) {
> >+ *prev = vma;
> >+ goto success;
> >+ }
> >+
> >+
> >+ pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
> >+ *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
> >+ vma->vm_file, pgoff, vma_policy(vma), &purged);
> >+ if (*prev) {
> >+ vma = *prev;
> >+ goto success;
> >+ }
> >+
> >+ *prev = vma;
> >+
> >+ if (start != vma->vm_start) {
> >+ error = split_vma(mm, vma, start, 1);
> >+ if (error)
> >+ goto out;
> >+ }
> >+
> >+ if (end != vma->vm_end) {
> >+ error = split_vma(mm, vma, end, 0);
> >+ if (error)
> >+ goto out;
> >+ }
> >+
> >+success:
> >+ /* V6. VVPPVV -> VVNNVV */
> >+ vma_lock_anon_vma(vma);
> >+ *is_purged |= (vma->purged|purged);
> >+ vma_unlock_anon_vma(vma);
> >+
> >+ vma->vm_flags = new_flags;
> >+ vma->purged = false;
> >+ return 0;
> >+out:
> >+ return error;
> >+}
> >+
> >+/* I didn't look into KSM/Hugepage so disalbed them */
> >+#define VM_NO_VOLATILE (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|\
> >+ VM_MERGEABLE|VM_HUGEPAGE|VM_LOCKED)
> >+
> >+static int do_mvolatile(struct vm_area_struct *vma,
> >+ struct vm_area_struct **prev, unsigned long start, unsigned long end)
> >+{
> >+ int error = -EINVAL;
> >+ vm_flags_t new_flags = vma->vm_flags;
> >+ struct mm_struct *mm = vma->vm_mm;
> >+
> >+ new_flags |= VM_VOLATILE;
> >+
> >+ /* Note : Current version doesn't support file vma volatile */
> >+ if (vma->vm_file) {
> >+ *prev = vma;
> >+ goto out;
> >+ }
> >+
> >+ if (vma->vm_flags & VM_NO_VOLATILE ||
> >+ (vma == get_gate_vma(current->mm))) {
> >+ *prev = vma;
> >+ goto out;
> >+ }
> >+ /*
> >+ * In case of calling MADV_VOLATILE again,
> >+ * We just reset purged state.
> >+ */
> >+ if (new_flags == vma->vm_flags) {
> >+ *prev = vma;
> >+ vma_lock_anon_vma(vma);
> >+ vma->purged = false;
> >+ vma_unlock_anon_vma(vma);
> >+ error = 0;
> >+ goto out;
> >+ }
> >+
> >+ *prev = vma;
> >+
> >+ if (start != vma->vm_start) {
> >+ error = split_vma(mm, vma, start, 1);
> >+ if (error)
> >+ goto out;
> >+ }
> >+
> >+ if (end != vma->vm_end) {
> >+ error = split_vma(mm, vma, end, 0);
> >+ if (error)
> >+ goto out;
> >+ }
> >+
> >+ error = 0;
> >+
> >+ vma_lock_anon_vma(vma);
> >+ vma->vm_flags = new_flags;
> >+ vma_unlock_anon_vma(vma);
> >+out:
> >+ return error;
> >+}
> >+
> >+/*
> >+ * Return -EINVAL if range doesn't include a right vma at all.
> >+ * Return -ENOMEM with interrupting range opeartion if memory is not enough to
> >+ * merge/split vmas.
> >+ * Return 0 if range consists of only proper vmas.
> >+ * Return 1 if part of range includes inavlid area(ex, hole/huge/ksm/mlock/
> >+ * special area)
> >+ */
> >+SYSCALL_DEFINE2(mvolatile, unsigned long, start, size_t, len)
> >+{
> >+ unsigned long end, tmp;
> >+ struct vm_area_struct *vma, *prev;
> >+ bool invalid = false;
> >+ int error = -EINVAL;
> >+
> >+ down_write(¤t->mm->mmap_sem);
> >+ if (start & ~PAGE_MASK)
> >+ goto out;
> >+
> >+ len &= PAGE_MASK;
> >+ if (!len)
> >+ goto out;
> >+
> >+ end = start + len;
> >+ if (end < start)
> >+ goto out;
> >+
> >+ vma = find_vma_prev(current->mm, start, &prev);
> >+ if (!vma)
> >+ goto out;
> >+
> >+ if (start > vma->vm_start)
> >+ prev = vma;
> >+
> >+ for (;;) {
> >+ /* Here start < (end|vma->vm_end). */
> >+ if (start < vma->vm_start) {
> >+ start = vma->vm_start;
> >+ if (start >= end)
> >+ goto out;
> >+ invalid = true;
> >+ }
> >+
> >+ /* Here vma->vm_start <= start < (end|vma->vm_end) */
> >+ tmp = vma->vm_end;
> >+ if (end < tmp)
> >+ tmp = end;
> >+
> >+ /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
> >+ error = do_mvolatile(vma, &prev, start, tmp);
> >+ if (error == -ENOMEM) {
> >+ up_write(¤t->mm->mmap_sem);
> >+ return error;
> >+ }
> >+ if (error == -EINVAL)
> >+ invalid = true;
> >+ else
> >+ error = 0;
> >+ start = tmp;
> >+ if (prev && start < prev->vm_end)
> >+ start = prev->vm_end;
> >+ if (start >= end)
> >+ break;
> >+
> >+ vma = prev->vm_next;
> >+ if (!vma)
> >+ break;
> >+ }
> >+out:
> >+ up_write(¤t->mm->mmap_sem);
> >+ return invalid ? 1 : 0;
> >+}
> >+/*
> >+ * Return -ENOMEM with interrupting range opeartion if memory is not enough
> >+ * to merge/split vmas.
> >+ * Return 1 if part of range includes purged's one, otherwise, return 0
> >+ */
> >+SYSCALL_DEFINE2(mnovolatile, unsigned long, start, size_t, len)
> >+{
> >+ unsigned long end, tmp;
> >+ struct vm_area_struct *vma, *prev;
> >+ int ret, error = -EINVAL;
> >+ bool is_purged = false;
> >+
> >+ down_write(¤t->mm->mmap_sem);
> >+ if (start & ~PAGE_MASK)
> >+ goto out;
> >+
> >+ len &= PAGE_MASK;
> >+ if (!len)
> >+ goto out;
> >+
> >+ end = start + len;
> >+ if (end < start)
> >+ goto out;
> >+
> >+ vma = find_vma_prev(current->mm, start, &prev);
> >+ if (!vma)
> >+ goto out;
> >+
> >+ if (start > vma->vm_start)
> >+ prev = vma;
> >+
> >+ for (;;) {
> >+ /* Here start < (end|vma->vm_end). */
> >+ if (start < vma->vm_start) {
> >+ start = vma->vm_start;
> >+ if (start >= end)
> >+ goto out;
> >+ }
> >+
> >+ /* Here vma->vm_start <= start < (end|vma->vm_end) */
> >+ tmp = vma->vm_end;
> >+ if (end < tmp)
> >+ tmp = end;
> >+
> >+ /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
> >+ error = do_mnovolatile(vma, &prev, start, tmp, &is_purged);
> >+ if (error) {
> >+ WARN_ON(error != -ENOMEM);
> >+ goto out;
> >+ }
> >+ start = tmp;
> >+ if (prev && start < prev->vm_end)
> >+ start = prev->vm_end;
> >+ if (start >= end)
> >+ break;
> >+
> >+ vma = prev->vm_next;
> >+ if (!vma)
> >+ break;
> >+ }
> >+out:
> >+ up_write(¤t->mm->mmap_sem);
> >+
> >+ if (error)
> >+ ret = error;
> >+ else if (is_purged)
> >+ ret = PURGED;
> >+ else
> >+ ret = NO_PURGED;
> >+
> >+ return ret;
> >+}
> >+#endif
> >diff --git a/mm/rmap.c b/mm/rmap.c
> >index 2ee1ef0..402d9da 100644
> >--- a/mm/rmap.c
> >+++ b/mm/rmap.c
> >@@ -57,6 +57,7 @@
> > #include <linux/migrate.h>
> > #include <linux/hugetlb.h>
> > #include <linux/backing-dev.h>
> >+#include <linux/mvolatile.h>
> > #include <asm/tlbflush.h>
> >@@ -308,6 +309,7 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
> > vma->anon_vma = anon_vma;
> > anon_vma_lock(anon_vma);
> > anon_vma_chain_link(vma, avc, anon_vma);
> >+ vma_purge_copy(vma, pvma);
> > anon_vma_unlock(anon_vma);
> > return 0;
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@...ck.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>
--
Kind regards,
Minchan Kim
--
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