[PATCH] mm: introduce for_each_vma helpers

From: Davidlohr Bueso
Date: Tue Aug 12 2014 - 13:45:39 EST

The most common way of iterating through the list of vmas, is via:
for (vma = mm->mmap; vma; vma = vma->vm_next)

This patch replaces this logic with a new for_each_vma(vma) helper,
which 1) encapsulates this logic, and 2) make it easier to read.
It also updates most of the callers, so its a pretty good start.

Similarly, we also have for_each_vma_start(vma, start) when the user
does not want to start at the beginning of the list. And lastly the
for_each_vma_start_inc(vma, start, inc) helper in introduced to allow
users to create higher level special vma abstractions, such as with
the case of ELF binaries.

Signed-off-by: Davidlohr Bueso <davidlohr@xxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: "James E.J. Bottomley" <jejb@xxxxxxxxxxxxxxxx>
Cc: Helge Deller <deller@xxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Robert Richter <rric@xxxxxxxxxx>
---
Tested on x86-64, survives multiple kernel builds.
Not tested: nommu, s390, parisc, powerpc, oprofile.
Applies on Linus' latest.

arch/parisc/kernel/cache.c | 6 +++---
arch/powerpc/oprofile/cell/spu_task_sync.c | 2 +-
arch/s390/mm/pgtable.c | 2 +-
drivers/oprofile/buffer_sync.c | 3 +--
fs/binfmt_elf.c | 17 ++++++++++-------
fs/binfmt_elf_fdpic.c | 18 +++++++++++-------
fs/proc/base.c | 5 ++---
fs/proc/task_mmu.c | 3 ++-
include/linux/mm.h | 9 +++++++++
kernel/events/uprobes.c | 4 ++--
kernel/sys.c | 2 +-
mm/ksm.c | 2 +-
mm/memcontrol.c | 9 ++++++---
mm/mempolicy.c | 2 +-
mm/migrate.c | 4 +++-
mm/mlock.c | 9 +++++----
mm/mmap.c | 8 ++++----
mm/nommu.c | 4 ++--
mm/swapfile.c | 3 ++-
19 files changed, 67 insertions(+), 45 deletions(-)

diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index f6448c7..7222b49 100644
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -462,7 +462,7 @@ static inline unsigned long mm_total_size(struct mm_struct *mm)
struct vm_area_struct *vma;
unsigned long usize = 0;

- for (vma = mm->mmap; vma; vma = vma->vm_next)
+ for_each_vma(vma)
usize += vma->vm_end - vma->vm_start;
return usize;
}
@@ -495,7 +495,7 @@ void flush_cache_mm(struct mm_struct *mm)
}

if (mm->context == mfsp(3)) {
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
flush_user_dcache_range_asm(vma->vm_start, vma->vm_end);
if ((vma->vm_flags & VM_EXEC) == 0)
continue;
@@ -505,7 +505,7 @@ void flush_cache_mm(struct mm_struct *mm)
}

pgd = mm->pgd;
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
unsigned long addr;

for (addr = vma->vm_start; addr < vma->vm_end;
diff --git a/arch/powerpc/oprofile/cell/spu_task_sync.c b/arch/powerpc/oprofile/cell/spu_task_sync.c
index 28f1af2..862d076 100644
--- a/arch/powerpc/oprofile/cell/spu_task_sync.c
+++ b/arch/powerpc/oprofile/cell/spu_task_sync.c
@@ -335,7 +335,7 @@ get_exec_dcookie_and_offset(struct spu *spu, unsigned int *offsetp,
mm->exe_file->f_dentry->d_name.name);
}

- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
if (vma->vm_start > spu_ref || vma->vm_end <= spu_ref)
continue;
my_offset = spu_ref - vma->vm_start;
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 19daa53..d57a614 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -1260,7 +1260,7 @@ static inline void thp_split_mm(struct mm_struct *mm)
{
struct vm_area_struct *vma;

- for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
+ for_each_vma(vma) {
thp_split_vma(vma);
vma->vm_flags &= ~VM_HUGEPAGE;
vma->vm_flags |= VM_NOHUGEPAGE;
diff --git a/drivers/oprofile/buffer_sync.c b/drivers/oprofile/buffer_sync.c
index d93b2b6..415a0c0 100644
--- a/drivers/oprofile/buffer_sync.c
+++ b/drivers/oprofile/buffer_sync.c
@@ -243,8 +243,7 @@ lookup_dcookie(struct mm_struct *mm, unsigned long addr, off_t *offset)
unsigned long cookie = NO_COOKIE;
struct vm_area_struct *vma;

- for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
-
+ for_each_vma_start(vma, find_vma(mm, addr)) {
if (addr < vma->vm_start || addr >= vma->vm_end)
continue;

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 3892c1a..fd25e7f 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1406,6 +1406,7 @@ static void fill_siginfo_note(struct memelfnote *note, user_siginfo_t *csigdata,
static int fill_files_note(struct memelfnote *note)
{
struct vm_area_struct *vma;
+ struct mm_struct *mm = current->mm;
unsigned count, size, names_ofs, remaining, n;
user_long_t *data;
user_long_t *start_end_ofs;
@@ -1428,7 +1429,8 @@ static int fill_files_note(struct memelfnote *note)
name_base = name_curpos = ((char *)data) + names_ofs;
remaining = size - names_ofs;
count = 0;
- for (vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
+
+ for_each_vma(vma) {
struct file *file;
const char *filename;

@@ -1993,6 +1995,10 @@ static struct vm_area_struct *next_vma(struct vm_area_struct *this_vma,
return gate_vma;
}

+#define for_each_vma_gate(vma) \
+ for_each_vma_start_inc((vma), first_vma(current, gate_vma), \
+ next_vma((vma), gate_vma))
+
static void fill_extnum_info(struct elfhdr *elf, struct elf_shdr *shdr4extnum,
elf_addr_t e_shoff, int segs)
{
@@ -2015,8 +2021,7 @@ static size_t elf_core_vma_data_size(struct vm_area_struct *gate_vma,
struct vm_area_struct *vma;
size_t size = 0;

- for (vma = first_vma(current, gate_vma); vma != NULL;
- vma = next_vma(vma, gate_vma))
+ for_each_vma_gate(vma)
size += vma_dump_size(vma, mm_flags);
return size;
}
@@ -2128,8 +2133,7 @@ static int elf_core_dump(struct coredump_params *cprm)
goto end_coredump;

/* Write program headers for segments dump */
- for (vma = first_vma(current, gate_vma); vma != NULL;
- vma = next_vma(vma, gate_vma)) {
+ for_each_vma_gate(vma) {
struct elf_phdr phdr;

phdr.p_type = PT_LOAD;
@@ -2164,8 +2168,7 @@ static int elf_core_dump(struct coredump_params *cprm)
if (!dump_skip(cprm, dataoff - cprm->written))
goto end_coredump;

- for (vma = first_vma(current, gate_vma); vma != NULL;
- vma = next_vma(vma, gate_vma)) {
+ for_each_vma_gate(vma) {
unsigned long addr;
unsigned long end;

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index fe2a643..aea8ac7 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1484,9 +1484,10 @@ static void fill_extnum_info(struct elfhdr *elf, struct elf_shdr *shdr4extnum,
*/
static bool elf_fdpic_dump_segments(struct coredump_params *cprm)
{
+ struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;

- for (vma = current->mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
unsigned long addr;

if (!maydump(vma, cprm->mm_flags))
@@ -1520,11 +1521,13 @@ static bool elf_fdpic_dump_segments(struct coredump_params *cprm)
static size_t elf_core_vma_data_size(unsigned long mm_flags)
{
struct vm_area_struct *vma;
+ struct mm_struct *mm = current->mm;
size_t size = 0;

- for (vma = current->mm->mmap; vma; vma = vma->vm_next)
+ for_each_vma(vma) {
if (maydump(vma, mm_flags))
size += vma->vm_end - vma->vm_start;
+ }
return size;
}

@@ -1563,6 +1566,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
elf_addr_t e_shoff;
struct core_thread *ct;
struct elf_thread_status *tmp;
+ struct mm_struct *mm = current->mm;

/*
* We no longer stop all VM operations.
@@ -1598,7 +1602,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
goto cleanup;
#endif

- for (ct = current->mm->core_state->dumper.next;
+ for (ct = mm->core_state->dumper.next;
ct; ct = ct->next) {
tmp = kzalloc(sizeof(*tmp), GFP_KERNEL);
if (!tmp)
@@ -1621,7 +1625,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
fill_prstatus(prstatus, current, cprm->siginfo->si_signo);
elf_core_copy_regs(&prstatus->pr_reg, cprm->regs);

- segs = current->mm->map_count;
+ segs = mm->map_count;
segs += elf_core_extra_phdrs();

/* for notes section */
@@ -1642,12 +1646,12 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
*/

fill_note(notes + 0, "CORE", NT_PRSTATUS, sizeof(*prstatus), prstatus);
- fill_psinfo(psinfo, current->group_leader, current->mm);
+ fill_psinfo(psinfo, current->group_leader, mm);
fill_note(notes + 1, "CORE", NT_PRPSINFO, sizeof(*psinfo), psinfo);

numnote = 2;

- auxv = (elf_addr_t *) current->mm->saved_auxv;
+ auxv = (elf_addr_t *) mm->saved_auxv;

i = 0;
do
@@ -1713,7 +1717,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
goto end_coredump;

/* write program headers for segments dump */
- for (vma = current->mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
struct elf_phdr phdr;
size_t sz;

diff --git a/fs/proc/base.c b/fs/proc/base.c
index baf852b..2438695 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1872,7 +1872,7 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
struct vm_area_struct *vma;
struct task_struct *task;
struct mm_struct *mm;
- unsigned long nr_files, pos, i;
+ unsigned long nr_files, pos = 2, i;
struct flex_array *fa = NULL;
struct map_files_info info;
struct map_files_info *p;
@@ -1911,8 +1911,7 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
* otherwise we get lockdep complained, since filldir()
* routine might require mmap_sem taken in might_fault().
*/
-
- for (vma = mm->mmap, pos = 2; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
if (vma->vm_file && ++pos > ctx->pos)
nr_files++;
}
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index dfc791c..ba7f71c 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -831,7 +831,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
down_read(&mm->mmap_sem);
if (type == CLEAR_REFS_SOFT_DIRTY)
mmu_notifier_invalidate_range_start(mm, 0, -1);
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+
+ for_each_vma(vma) {
cp.vma = vma;
if (is_vm_hugetlb_page(vma))
continue;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8981cc8..a5ffacd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1734,6 +1734,15 @@ struct vm_area_struct *vma_interval_tree_iter_first(struct rb_root *root,
struct vm_area_struct *vma_interval_tree_iter_next(struct vm_area_struct *node,
unsigned long start, unsigned long last);

+#define for_each_vma(vma) \
+ for ((vma) = mm->mmap; (vma); (vma) = (vma)->vm_next)
+
+#define for_each_vma_start(vma, start) \
+ for ((vma) = (start); (vma); (vma) = (vma)->vm_next)
+
+#define for_each_vma_start_inc(vma, start, inc) \
+ for ((vma) = (start); (vma); (vma) = (inc))
+
#define vma_interval_tree_foreach(vma, root, start, last) \
for (vma = vma_interval_tree_iter_first(root, start, last); \
vma; vma = vma_interval_tree_iter_next(vma, start, last))
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 1d0af8a..fccd3fe 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -969,7 +969,7 @@ static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm)
int err = 0;

down_read(&mm->mmap_sem);
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
unsigned long vaddr;
loff_t offset;

@@ -1651,7 +1651,7 @@ static void mmf_recalc_uprobes(struct mm_struct *mm)
{
struct vm_area_struct *vma;

- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
if (!valid_vma(vma, false))
continue;
/*
diff --git a/kernel/sys.c b/kernel/sys.c
index ce81291..2827d5b 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1663,7 +1663,7 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
if (mm->exe_file) {
struct vm_area_struct *vma;

- for (vma = mm->mmap; vma; vma = vma->vm_next)
+ for_each_vma(vma)
if (vma->vm_file &&
path_equal(&vma->vm_file->f_path,
&mm->exe_file->f_path))
diff --git a/mm/ksm.c b/mm/ksm.c
index fb75902..6092b2a 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -780,7 +780,7 @@ static int unmerge_and_remove_all_rmap_items(void)
mm_slot != &ksm_mm_head; mm_slot = ksm_scan.mm_slot) {
mm = mm_slot->mm;
down_read(&mm->mmap_sem);
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
if (ksm_test_exit(mm))
break;
if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ec4dcf1..b9383c0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5918,7 +5918,7 @@ static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
struct vm_area_struct *vma;

down_read(&mm->mmap_sem);
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
struct mm_walk mem_cgroup_count_precharge_walk = {
.pmd_entry = mem_cgroup_count_precharge_pte_range,
.mm = mm,
@@ -6180,23 +6180,26 @@ retry:
cond_resched();
goto retry;
}
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+
+ for_each_vma(vma) {
int ret;
struct mm_walk mem_cgroup_move_charge_walk = {
.pmd_entry = mem_cgroup_move_charge_pte_range,
.mm = mm,
.private = vma,
};
+
if (is_vm_hugetlb_page(vma))
continue;
ret = walk_page_range(vma->vm_start, vma->vm_end,
&mem_cgroup_move_charge_walk);
- if (ret)
+ if (ret) {
/*
* means we have consumed all precharges and failed in
* doing additional charge. Just abandon here.
*/
break;
+ }
}
up_read(&mm->mmap_sem);
}
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 8f5330d..8abc94f 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -453,7 +453,7 @@ void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
struct vm_area_struct *vma;

down_write(&mm->mmap_sem);
- for (vma = mm->mmap; vma; vma = vma->vm_next)
+ for_each_vma(vma)
mpol_rebind_policy(vma->vm_policy, new, MPOL_REBIND_ONCE);
up_write(&mm->mmap_sem);
}
diff --git a/mm/migrate.c b/mm/migrate.c
index f78ec9b..0a62a2d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1544,7 +1544,9 @@ int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
struct vm_area_struct *vma;
int err = 0;

- for (vma = mm->mmap; vma && !err; vma = vma->vm_next) {
+ for_each_vma(vma) {
+ if (err)
+ break;
if (vma->vm_ops && vma->vm_ops->migrate) {
err = vma->vm_ops->migrate(vma, to, from, flags);
if (err)
diff --git a/mm/mlock.c b/mm/mlock.c
index ce84cb0..434b4b0 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -771,16 +771,17 @@ SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)

static int do_mlockall(int flags)
{
- struct vm_area_struct * vma, * prev = NULL;
+ struct vm_area_struct *vma, *prev = NULL;
+ struct mm_struct *mm = current->mm;

if (flags & MCL_FUTURE)
- current->mm->def_flags |= VM_LOCKED;
+ mm->def_flags |= VM_LOCKED;
else
- current->mm->def_flags &= ~VM_LOCKED;
+ mm->def_flags &= ~VM_LOCKED;
if (flags == MCL_FUTURE)
goto out;

- for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
+ for_each_vma(vma) {
vm_flags_t newflags;

newflags = vma->vm_flags & ~VM_LOCKED;
diff --git a/mm/mmap.c b/mm/mmap.c
index c1f2ea4..7255274 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -574,7 +574,7 @@ static unsigned long count_vma_pages_range(struct mm_struct *mm,
max(addr, vma->vm_start)) >> PAGE_SHIFT;

/* Iterate over the rest of the overlaps */
- for (vma = vma->vm_next; vma; vma = vma->vm_next) {
+ for_each_vma_start(vma, vma->vm_next) {
unsigned long overlap_len;

if (vma->vm_start > end)
@@ -3108,14 +3108,14 @@ int mm_take_all_locks(struct mm_struct *mm)

mutex_lock(&mm_all_locks_mutex);

- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
if (signal_pending(current))
goto out_unlock;
if (vma->vm_file && vma->vm_file->f_mapping)
vm_lock_mapping(mm, vma->vm_file->f_mapping);
}

- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
if (signal_pending(current))
goto out_unlock;
if (vma->anon_vma)
@@ -3178,7 +3178,7 @@ void mm_drop_all_locks(struct mm_struct *mm)
BUG_ON(down_read_trylock(&mm->mmap_sem));
BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));

- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
if (vma->anon_vma)
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
vm_unlock_anon_vma(avc->anon_vma);
diff --git a/mm/nommu.c b/mm/nommu.c
index a881d96..c150415 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -843,7 +843,7 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)

/* trawl the list (there may be multiple mappings in which addr
* resides) */
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
if (vma->vm_start > addr)
return NULL;
if (vma->vm_end > addr) {
@@ -892,7 +892,7 @@ static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,

/* trawl the list (there may be multiple mappings in which addr
* resides) */
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ for_each_vma(vma) {
if (vma->vm_start < addr)
continue;
if (vma->vm_start > addr)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 8798b2e..eeb1d24 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1266,7 +1266,8 @@ static int unuse_mm(struct mm_struct *mm,
down_read(&mm->mmap_sem);
lock_page(page);
}
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+
+ for_each_vma(vma) {
if (vma->anon_vma && (ret = unuse_vma(vma, entry, page)))
break;
}
--
1.8.1.4



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