[PATCH v4 2/2] zram: try vmalloc() after kmalloc()

[Sergey Senozhatsky]

From: Kyeongdon Kim <kyeongdon.kim@xxxxxxx>

When we're using LZ4 multi compression streams for zram swap, we found out
page allocation failure message in system running test.  That was not only
once, but a few(2 - 5 times per test).  Also, some failure cases were
continually occurring to try allocation order 3.

In order to make parallel compression private data, we should call
kzalloc() with order 2/3 in runtime(lzo/lz4).  But if there is no order
2/3 size memory to allocate in that time, page allocation fails.  This
patch makes to use vmalloc() as fallback of kmalloc(), this prevents page
alloc failure warning.

After using this, we never found warning message in running test, also It
could reduce process startup latency about 60-120ms in each case.

For reference a call trace :

Binder_1: page allocation failure: order:3, mode:0x10c0d0
CPU: 0 PID: 424 Comm: Binder_1 Tainted: GW 3.10.49-perf-g991d02b-dirty #20
Call trace:
[<ffffffc0002069c8>] dump_backtrace+0x0/0x270
[<ffffffc000206c48>] show_stack+0x10/0x1c
[<ffffffc000cb51c8>] dump_stack+0x1c/0x28
[<ffffffc0002bbfc8>] warn_alloc_failed+0xfc/0x11c
[<ffffffc0002bf518>] __alloc_pages_nodemask+0x724/0x7f0
[<ffffffc0002bf5f8>] __get_free_pages+0x14/0x5c
[<ffffffc0002ed6a4>] kmalloc_order_trace+0x38/0xd8
[<ffffffc0005d9738>] zcomp_lz4_create+0x2c/0x38
[<ffffffc0005d78f0>] zcomp_strm_alloc+0x34/0x78
[<ffffffc0005d7a58>] zcomp_strm_multi_find+0x124/0x1ec
[<ffffffc0005d7c14>] zcomp_strm_find+0xc/0x18
[<ffffffc0005d8fa0>] zram_bvec_rw+0x2fc/0x780
[<ffffffc0005d9680>] zram_make_request+0x25c/0x2d4
[<ffffffc00040f8ac>] generic_make_request+0x80/0xbc
[<ffffffc00040f98c>] submit_bio+0xa4/0x15c
[<ffffffc0002e8bb0>] __swap_writepage+0x218/0x230
[<ffffffc0002e8c04>] swap_writepage+0x3c/0x4c
[<ffffffc0002c7384>] shrink_page_list+0x51c/0x8d0
[<ffffffc0002c7e88>] shrink_inactive_list+0x3f8/0x60c
[<ffffffc0002c86c8>] shrink_lruvec+0x33c/0x4cc
[<ffffffc0002c8894>] shrink_zone+0x3c/0x100
[<ffffffc0002c8c10>] try_to_free_pages+0x2b8/0x54c
[<ffffffc0002bf308>] __alloc_pages_nodemask+0x514/0x7f0
[<ffffffc0002bf5f8>] __get_free_pages+0x14/0x5c
[<ffffffc0003446cc>] proc_info_read+0x50/0xe4
[<ffffffc0002f5204>] vfs_read+0xa0/0x12c
[<ffffffc0002f59c8>] SyS_read+0x44/0x74
DMA: 3397*4kB (MC) 26*8kB (RC) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB
     0*512kB 0*1024kB 0*2048kB 0*4096kB = 13796kB

[minchan@xxxxxxxxxx: change vmalloc gfp and adding comment about gfp]
[sergey.senozhatsky@xxxxxxxxx: tweak comments and styles]
Signed-off-by: Kyeongdon Kim <kyeongdon.kim@xxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
---
 drivers/block/zram/zcomp_lz4.c | 23 +++++++++++++++++++++--
 drivers/block/zram/zcomp_lzo.c | 23 +++++++++++++++++++++--
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/drivers/block/zram/zcomp_lz4.c b/drivers/block/zram/zcomp_lz4.c
index ee44b51..dd60831 100644
--- a/drivers/block/zram/zcomp_lz4.c
+++ b/drivers/block/zram/zcomp_lz4.c
@@ -10,17 +10,36 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/lz4.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
 
 #include "zcomp_lz4.h"
 
 static void *zcomp_lz4_create(void)
 {
-	return kzalloc(LZ4_MEM_COMPRESS, GFP_NOIO);
+	void *ret;
+
+	/*
+	 * This function can be called in swapout/fs write path
+	 * so we can't use GFP_FS|IO. And it assumes we already
+	 * have at least one stream in zram initialization so we
+	 * don't do best effort to allocate more stream in here.
+	 * A default stream will work well without further multiple
+	 * streams. That's why we use NORETRY | NOWARN.
+	 */
+	ret = kzalloc(LZ4_MEM_COMPRESS, GFP_NOIO | __GFP_NORETRY |
+					__GFP_NOWARN);
+	if (!ret)
+		ret = __vmalloc(LZ4_MEM_COMPRESS,
+				GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN |
+				__GFP_ZERO | __GFP_HIGHMEM,
+				PAGE_KERNEL);
+	return ret;
 }
 
 static void zcomp_lz4_destroy(void *private)
 {
-	kfree(private);
+	kvfree(private);
 }
 
 static int zcomp_lz4_compress(const unsigned char *src, unsigned char *dst,
diff --git a/drivers/block/zram/zcomp_lzo.c b/drivers/block/zram/zcomp_lzo.c
index 683ce04..edc5499 100644
--- a/drivers/block/zram/zcomp_lzo.c
+++ b/drivers/block/zram/zcomp_lzo.c
@@ -10,17 +10,36 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/lzo.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
 
 #include "zcomp_lzo.h"
 
 static void *lzo_create(void)
 {
-	return kzalloc(LZO1X_MEM_COMPRESS, GFP_NOIO);
+	void *ret;
+
+	/*
+	 * This function can be called in swapout/fs write path
+	 * so we can't use GFP_FS|IO. And it assumes we already
+	 * have at least one stream in zram initialization so we
+	 * don't do best effort to allocate more stream in here.
+	 * A default stream will work well without further multiple
+	 * streams. That's why we use NORETRY | NOWARN.
+	 */
+	ret = kzalloc(LZO1X_MEM_COMPRESS, GFP_NOIO | __GFP_NORETRY |
+					__GFP_NOWARN);
+	if (!ret)
+		ret = __vmalloc(LZO1X_MEM_COMPRESS,
+				GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN |
+				__GFP_ZERO | __GFP_HIGHMEM,
+				PAGE_KERNEL);
+	return ret;
 }
 
 static void lzo_destroy(void *private)
 {
-	kfree(private);
+	kvfree(private);
 }
 
 static int lzo_compress(const unsigned char *src, unsigned char *dst,
-- 
2.6.2

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