[PATCH v7 1/4] mm/vmalloc: don't set area->caller twice

[PATCH v7 1/4] mm/vmalloc: don't set area->caller twice

[Wanpeng Li]

Changelog:
 *v1 -> v2: rebase against mmotm tree
 *v6 -> v7: drop "caller" argument of __vmalloc_area_node()

The caller address has already been set in set_vmalloc_vm(), there's no need
to set it again in __vmalloc_area_node.

Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
---
 mm/vmalloc.c |    7 +++----
 1 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 1074543..f75c2aa 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1546,7 +1546,7 @@ static void *__vmalloc_node(unsigned long size, unsigned long align,
 			    gfp_t gfp_mask, pgprot_t prot,
 			    int node, const void *caller);
 static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
-				 pgprot_t prot, int node, const void *caller)
+				 pgprot_t prot, int node)
 {
 	const int order = 0;
 	struct page **pages;
@@ -1560,13 +1560,12 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 	/* Please note that the recursion is strictly bounded. */
 	if (array_size > PAGE_SIZE) {
 		pages = __vmalloc_node(array_size, 1, nested_gfp|__GFP_HIGHMEM,
-				PAGE_KERNEL, node, caller);
+				PAGE_KERNEL, node, area->caller);
 		area->flags |= VM_VPAGES;
 	} else {
 		pages = kmalloc_node(array_size, nested_gfp, node);
 	}
 	area->pages = pages;
-	area->caller = caller;
 	if (!area->pages) {
 		remove_vm_area(area->addr);
 		kfree(area);
@@ -1634,7 +1633,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
 	if (!area)
 		goto fail;
 
-	addr = __vmalloc_area_node(area, gfp_mask, prot, node, caller);
+	addr = __vmalloc_area_node(area, gfp_mask, prot, node);
 	if (!addr)
 		goto fail;
 
-- 
1.7.5.4

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[PATCH v7 2/4] mm/vmalloc: fix show vmap_area information race with vmap_area tear down

[Wanpeng Li]

Changelog:
 *v4 -> v5: return directly for !VM_VM_AREA case and remove (VM_LAZY_FREE | VM_LAZY_FREEING) check
 *v5 -> v6: add KOSAKI's ack

There is a race window between vmap_area tear down and show vmap_area information.

	A                                                B

remove_vm_area
spin_lock(&vmap_area_lock);
va->vm = NULL;
va->flags &= ~VM_VM_AREA;
spin_unlock(&vmap_area_lock);
						spin_lock(&vmap_area_lock);
						if (va->flags & (VM_LAZY_FREE | VM_LAZY_FREEZING))
							return 0;
						if (!(va->flags & VM_VM_AREA)) {
							seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n",
								(void *)va->va_start, (void *)va->va_end,
								va->va_end - va->va_start);
							return 0;
						}
free_unmap_vmap_area(va);
	flush_cache_vunmap
	free_unmap_vmap_area_noflush
		unmap_vmap_area
		free_vmap_area_noflush
			va->flags |= VM_LAZY_FREE

The assumption !VM_VM_AREA represents vm_map_ram allocation is introduced by
commit: d4033afd(mm, vmalloc: iterate vmap_area_list, instead of vmlist, in
vmallocinfo()). However, !VM_VM_AREA also represents vmap_area is being tear
down in race window mentioned above. This patch fix it by don't dump any
information for !VM_VM_AREA case and also remove (VM_LAZY_FREE | VM_LAZY_FREEING)
check since they are not possible for !VM_VM_AREA case.

Suggested-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
---
 mm/vmalloc.c |   13 +++++--------
 1 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f75c2aa..7647e69 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2578,15 +2578,12 @@ static int s_show(struct seq_file *m, void *p)
 	struct vmap_area *va = p;
 	struct vm_struct *v;
 
-	if (va->flags & (VM_LAZY_FREE | VM_LAZY_FREEING))
-		return 0;
-
-	if (!(va->flags & VM_VM_AREA)) {
-		seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n",
-			(void *)va->va_start, (void *)va->va_end,
-					va->va_end - va->va_start);
+	/*
+	 * s_show can encounter race with remove_vm_area, !VM_VM_AREA on
+	 * behalf of vmap area is being tear down or vm_map_ram allocation.
+	 */
+	if (!(va->flags & VM_VM_AREA))
 		return 0;
-	}
 
 	v = va->vm;
 
-- 
1.7.5.4

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[PATCH v7 3/4] mm/vmalloc: revert "mm/vmalloc.c: check VM_UNINITIALIZED flag in s_show instead of show_numa_info"

[Wanpeng Li]

Changelog:
 *v2 -> v3: revert commit d157a558 directly

The VM_UNINITIALIZED/VM_UNLIST flag introduced by commit f5252e00(mm: avoid
null pointer access in vm_struct via /proc/vmallocinfo) is used to avoid
accessing the pages field with unallocated page when show_numa_info() is
called. This patch move the check just before show_numa_info in order that
some messages still can be dumped via /proc/vmallocinfo. This patch revert
commit d157a558 (mm/vmalloc.c: check VM_UNINITIALIZED flag in s_show instead
of show_numa_info);

Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
---
 mm/vmalloc.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 7647e69..e523a14 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2562,6 +2562,11 @@ static void show_numa_info(struct seq_file *m, struct vm_struct *v)
 		if (!counters)
 			return;
 
+		/* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
+		smp_rmb();
+		if (v->flags & VM_UNINITIALIZED)
+			return;
+
 		memset(counters, 0, nr_node_ids * sizeof(unsigned int));
 
 		for (nr = 0; nr < v->nr_pages; nr++)
@@ -2587,11 +2592,6 @@ static int s_show(struct seq_file *m, void *p)
 
 	v = va->vm;
 
-	/* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
-	smp_rmb();
-	if (v->flags & VM_UNINITIALIZED)
-		return 0;
-
 	seq_printf(m, "0x%pK-0x%pK %7ld",
 		v->addr, v->addr + v->size, v->size);
 
-- 
1.7.5.4

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[PATCH v7 4/4] revert mm/vmalloc.c: emit the failure message before return

[Wanpeng Li]

Changelog:
 *v2 -> v3: revert commit 46c001a2 directly

Don't warning twice in __vmalloc_area_node and __vmalloc_node_range if
__vmalloc_area_node allocation failure. This patch revert commit 46c001a2
(mm/vmalloc.c: emit the failure message before return).

Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
---
 mm/vmalloc.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index e523a14..fa4eee8 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1635,7 +1635,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
 
 	addr = __vmalloc_area_node(area, gfp_mask, prot, node);
 	if (!addr)
-		goto fail;
+		return NULL;
 
 	/*
 	 * In this function, newly allocated vm_struct has VM_UNINITIALIZED
-- 
1.7.5.4

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