zsmalloc: introduce obj_allocated

The usage pattern for obj_to_head is to check whether the zpage is
allocated or not.  Thus, introduce obj_allocated.

Link: https://lkml.kernel.org/r/20211115185909.3949505-5-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index c45807f..5c72fd5 100644 (file)
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -877,13 +877,21 @@ static unsigned long handle_to_obj(unsigned long handle)
        return *(unsigned long *)handle;
 }
 
-static unsigned long obj_to_head(struct page *page, void *obj)
+static bool obj_allocated(struct page *page, void *obj, unsigned long *phandle)
 {
+       unsigned long handle;
+
        if (unlikely(PageHugeObject(page))) {
                VM_BUG_ON_PAGE(!is_first_page(page), page);
-               return page->index;
+               handle = page->index;
        } else
-               return *(unsigned long *)obj;
+               handle = *(unsigned long *)obj;
+
+       if (!(handle & OBJ_ALLOCATED_TAG))
+               return false;
+
+       *phandle = handle & ~OBJ_ALLOCATED_TAG;
+       return true;
 }
 
 static inline int testpin_tag(unsigned long handle)
@@ -1606,7 +1614,6 @@ static void zs_object_copy(struct size_class *class, unsigned long dst,
 static unsigned long find_alloced_obj(struct size_class *class,
                                        struct page *page, int *obj_idx)
 {
-       unsigned long head;
        int offset = 0;
        int index = *obj_idx;
        unsigned long handle = 0;
@@ -1616,9 +1623,7 @@ static unsigned long find_alloced_obj(struct size_class *class,
        offset += class->size * index;
 
        while (offset < PAGE_SIZE) {
-               head = obj_to_head(page, addr + offset);
-               if (head & OBJ_ALLOCATED_TAG) {
-                       handle = head & ~OBJ_ALLOCATED_TAG;
+               if (obj_allocated(page, addr + offset, &handle)) {
                        if (trypin_tag(handle))
                                break;
                        handle = 0;
@@ -1928,7 +1933,7 @@ static int zs_page_migrate(struct address_space *mapping, struct page *newpage,
        struct page *dummy;
        void *s_addr, *d_addr, *addr;
        int offset, pos;
-       unsigned long handle, head;
+       unsigned long handle;
        unsigned long old_obj, new_obj;
        unsigned int obj_idx;
        int ret = -EAGAIN;
@@ -1964,9 +1969,7 @@ static int zs_page_migrate(struct address_space *mapping, struct page *newpage,
        pos = offset;
        s_addr = kmap_atomic(page);
        while (pos < PAGE_SIZE) {
-               head = obj_to_head(page, s_addr + pos);
-               if (head & OBJ_ALLOCATED_TAG) {
-                       handle = head & ~OBJ_ALLOCATED_TAG;
+               if (obj_allocated(page, s_addr + pos, &handle)) {
                        if (!trypin_tag(handle))
                                goto unpin_objects;
                }
@@ -1982,9 +1985,7 @@ static int zs_page_migrate(struct address_space *mapping, struct page *newpage,
 
        for (addr = s_addr + offset; addr < s_addr + pos;
                                        addr += class->size) {
-               head = obj_to_head(page, addr);
-               if (head & OBJ_ALLOCATED_TAG) {
-                       handle = head & ~OBJ_ALLOCATED_TAG;
+               if (obj_allocated(page, addr, &handle)) {
                        BUG_ON(!testpin_tag(handle));
 
                        old_obj = handle_to_obj(handle);
@@ -2029,9 +2030,7 @@ static int zs_page_migrate(struct address_space *mapping, struct page *newpage,
 unpin_objects:
        for (addr = s_addr + offset; addr < s_addr + pos;
                                                addr += class->size) {
-               head = obj_to_head(page, addr);
-               if (head & OBJ_ALLOCATED_TAG) {
-                       handle = head & ~OBJ_ALLOCATED_TAG;
+               if (obj_allocated(page, addr, &handle)) {
                        BUG_ON(!testpin_tag(handle));
                        unpin_tag(handle);
                }