Revision f6ba488073fe8159851fe398cc3c5ee383bb4c7a authored by Vladimir Davydov on 18 August 2017, 22:16:08 UTC, committed by Linus Torvalds on 18 August 2017, 22:32:01 UTC
To avoid a possible deadlock, sysfs_slab_remove() schedules an asynchronous work to delete sysfs entries corresponding to the kmem cache. To ensure the cache isn't freed before the work function is called, it takes a reference to the cache kobject. The reference is supposed to be released by the work function. However, the work function (sysfs_slab_remove_workfn()) does nothing in case the cache sysfs entry has already been deleted, leaking the kobject and the corresponding cache. This may happen on a per memcg cache destruction, because sysfs entries of a per memcg cache are deleted on memcg offline if the cache is empty (see __kmemcg_cache_deactivate()). The kmemleak report looks like this: unreferenced object 0xffff9f798a79f540 (size 32): comm "kworker/1:4", pid 15416, jiffies 4307432429 (age 28687.554s) hex dump (first 32 bytes): 6b 6d 61 6c 6c 6f 63 2d 31 36 28 31 35 39 39 3a kmalloc-16(1599: 6e 65 77 72 6f 6f 74 29 00 23 6b c0 ff ff ff ff newroot).#k..... backtrace: kmemleak_alloc+0x4a/0xa0 __kmalloc_track_caller+0x148/0x2c0 kvasprintf+0x66/0xd0 kasprintf+0x49/0x70 memcg_create_kmem_cache+0xe6/0x160 memcg_kmem_cache_create_func+0x20/0x110 process_one_work+0x205/0x5d0 worker_thread+0x4e/0x3a0 kthread+0x109/0x140 ret_from_fork+0x2a/0x40 unreferenced object 0xffff9f79b6136840 (size 416): comm "kworker/1:4", pid 15416, jiffies 4307432429 (age 28687.573s) hex dump (first 32 bytes): 40 fb 80 c2 3e 33 00 00 00 00 00 40 00 00 00 00 @...>3.....@.... 00 00 00 00 00 00 00 00 10 00 00 00 10 00 00 00 ................ backtrace: kmemleak_alloc+0x4a/0xa0 kmem_cache_alloc+0x128/0x280 create_cache+0x3b/0x1e0 memcg_create_kmem_cache+0x118/0x160 memcg_kmem_cache_create_func+0x20/0x110 process_one_work+0x205/0x5d0 worker_thread+0x4e/0x3a0 kthread+0x109/0x140 ret_from_fork+0x2a/0x40 Fix the leak by adding the missing call to kobject_put() to sysfs_slab_remove_workfn(). Link: http://lkml.kernel.org/r/20170812181134.25027-1-vdavydov.dev@gmail.com Fixes: 3b7b314053d02 ("slub: make sysfs file removal asynchronous") Signed-off-by: Vladimir Davydov <vdavydov.dev@gmail.com> Reported-by: Andrei Vagin <avagin@gmail.com> Tested-by: Andrei Vagin <avagin@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: <stable@vger.kernel.org> [4.12.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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test_bitmap.c
/*
* Test cases for printf facility.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/bitmap.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/string.h>
static unsigned total_tests __initdata;
static unsigned failed_tests __initdata;
static char pbl_buffer[PAGE_SIZE] __initdata;
static bool __init
__check_eq_uint(const char *srcfile, unsigned int line,
const unsigned int exp_uint, unsigned int x)
{
if (exp_uint != x) {
pr_warn("[%s:%u] expected %u, got %u\n",
srcfile, line, exp_uint, x);
return false;
}
return true;
}
static bool __init
__check_eq_bitmap(const char *srcfile, unsigned int line,
const unsigned long *exp_bmap, unsigned int exp_nbits,
const unsigned long *bmap, unsigned int nbits)
{
if (exp_nbits != nbits) {
pr_warn("[%s:%u] bitmap length mismatch: expected %u, got %u\n",
srcfile, line, exp_nbits, nbits);
return false;
}
if (!bitmap_equal(exp_bmap, bmap, nbits)) {
pr_warn("[%s:%u] bitmaps contents differ: expected \"%*pbl\", got \"%*pbl\"\n",
srcfile, line,
exp_nbits, exp_bmap, nbits, bmap);
return false;
}
return true;
}
static bool __init
__check_eq_pbl(const char *srcfile, unsigned int line,
const char *expected_pbl,
const unsigned long *bitmap, unsigned int nbits)
{
snprintf(pbl_buffer, sizeof(pbl_buffer), "%*pbl", nbits, bitmap);
if (strcmp(expected_pbl, pbl_buffer)) {
pr_warn("[%s:%u] expected \"%s\", got \"%s\"\n",
srcfile, line,
expected_pbl, pbl_buffer);
return false;
}
return true;
}
static bool __init
__check_eq_u32_array(const char *srcfile, unsigned int line,
const u32 *exp_arr, unsigned int exp_len,
const u32 *arr, unsigned int len)
{
if (exp_len != len) {
pr_warn("[%s:%u] array length differ: expected %u, got %u\n",
srcfile, line,
exp_len, len);
return false;
}
if (memcmp(exp_arr, arr, len*sizeof(*arr))) {
pr_warn("[%s:%u] array contents differ\n", srcfile, line);
print_hex_dump(KERN_WARNING, " exp: ", DUMP_PREFIX_OFFSET,
32, 4, exp_arr, exp_len*sizeof(*exp_arr), false);
print_hex_dump(KERN_WARNING, " got: ", DUMP_PREFIX_OFFSET,
32, 4, arr, len*sizeof(*arr), false);
return false;
}
return true;
}
#define __expect_eq(suffix, ...) \
({ \
int result = 0; \
total_tests++; \
if (!__check_eq_ ## suffix(__FILE__, __LINE__, \
##__VA_ARGS__)) { \
failed_tests++; \
result = 1; \
} \
result; \
})
#define expect_eq_uint(...) __expect_eq(uint, ##__VA_ARGS__)
#define expect_eq_bitmap(...) __expect_eq(bitmap, ##__VA_ARGS__)
#define expect_eq_pbl(...) __expect_eq(pbl, ##__VA_ARGS__)
#define expect_eq_u32_array(...) __expect_eq(u32_array, ##__VA_ARGS__)
static void __init test_zero_fill_copy(void)
{
DECLARE_BITMAP(bmap1, 1024);
DECLARE_BITMAP(bmap2, 1024);
bitmap_zero(bmap1, 1024);
bitmap_zero(bmap2, 1024);
/* single-word bitmaps */
expect_eq_pbl("", bmap1, 23);
bitmap_fill(bmap1, 19);
expect_eq_pbl("0-18", bmap1, 1024);
bitmap_copy(bmap2, bmap1, 23);
expect_eq_pbl("0-18", bmap2, 1024);
bitmap_fill(bmap2, 23);
expect_eq_pbl("0-22", bmap2, 1024);
bitmap_copy(bmap2, bmap1, 23);
expect_eq_pbl("0-18", bmap2, 1024);
bitmap_zero(bmap1, 23);
expect_eq_pbl("", bmap1, 1024);
/* multi-word bitmaps */
bitmap_zero(bmap1, 1024);
expect_eq_pbl("", bmap1, 1024);
bitmap_fill(bmap1, 109);
expect_eq_pbl("0-108", bmap1, 1024);
bitmap_copy(bmap2, bmap1, 1024);
expect_eq_pbl("0-108", bmap2, 1024);
bitmap_fill(bmap2, 1024);
expect_eq_pbl("0-1023", bmap2, 1024);
bitmap_copy(bmap2, bmap1, 1024);
expect_eq_pbl("0-108", bmap2, 1024);
/* the following tests assume a 32- or 64-bit arch (even 128b
* if we care)
*/
bitmap_fill(bmap2, 1024);
bitmap_copy(bmap2, bmap1, 109); /* ... but 0-padded til word length */
expect_eq_pbl("0-108,128-1023", bmap2, 1024);
bitmap_fill(bmap2, 1024);
bitmap_copy(bmap2, bmap1, 97); /* ... but aligned on word length */
expect_eq_pbl("0-108,128-1023", bmap2, 1024);
bitmap_zero(bmap2, 97); /* ... but 0-padded til word length */
expect_eq_pbl("128-1023", bmap2, 1024);
}
static void __init test_bitmap_u32_array_conversions(void)
{
DECLARE_BITMAP(bmap1, 1024);
DECLARE_BITMAP(bmap2, 1024);
u32 exp_arr[32], arr[32];
unsigned nbits;
for (nbits = 0 ; nbits < 257 ; ++nbits) {
const unsigned int used_u32s = DIV_ROUND_UP(nbits, 32);
unsigned int i, rv;
bitmap_zero(bmap1, nbits);
bitmap_set(bmap1, nbits, 1024 - nbits); /* garbage */
memset(arr, 0xff, sizeof(arr));
rv = bitmap_to_u32array(arr, used_u32s, bmap1, nbits);
expect_eq_uint(nbits, rv);
memset(exp_arr, 0xff, sizeof(exp_arr));
memset(exp_arr, 0, used_u32s*sizeof(*exp_arr));
expect_eq_u32_array(exp_arr, 32, arr, 32);
bitmap_fill(bmap2, 1024);
rv = bitmap_from_u32array(bmap2, nbits, arr, used_u32s);
expect_eq_uint(nbits, rv);
expect_eq_bitmap(bmap1, 1024, bmap2, 1024);
for (i = 0 ; i < nbits ; ++i) {
/*
* test conversion bitmap -> u32[]
*/
bitmap_zero(bmap1, 1024);
__set_bit(i, bmap1);
bitmap_set(bmap1, nbits, 1024 - nbits); /* garbage */
memset(arr, 0xff, sizeof(arr));
rv = bitmap_to_u32array(arr, used_u32s, bmap1, nbits);
expect_eq_uint(nbits, rv);
/* 1st used u32 words contain expected bit set, the
* remaining words are left unchanged (0xff)
*/
memset(exp_arr, 0xff, sizeof(exp_arr));
memset(exp_arr, 0, used_u32s*sizeof(*exp_arr));
exp_arr[i/32] = (1U<<(i%32));
expect_eq_u32_array(exp_arr, 32, arr, 32);
/* same, with longer array to fill
*/
memset(arr, 0xff, sizeof(arr));
rv = bitmap_to_u32array(arr, 32, bmap1, nbits);
expect_eq_uint(nbits, rv);
/* 1st used u32 words contain expected bit set, the
* remaining words are all 0s
*/
memset(exp_arr, 0, sizeof(exp_arr));
exp_arr[i/32] = (1U<<(i%32));
expect_eq_u32_array(exp_arr, 32, arr, 32);
/*
* test conversion u32[] -> bitmap
*/
/* the 1st nbits of bmap2 are identical to
* bmap1, the remaining bits of bmap2 are left
* unchanged (all 1s)
*/
bitmap_fill(bmap2, 1024);
rv = bitmap_from_u32array(bmap2, nbits,
exp_arr, used_u32s);
expect_eq_uint(nbits, rv);
expect_eq_bitmap(bmap1, 1024, bmap2, 1024);
/* same, with more bits to fill
*/
memset(arr, 0xff, sizeof(arr)); /* garbage */
memset(arr, 0, used_u32s*sizeof(u32));
arr[i/32] = (1U<<(i%32));
bitmap_fill(bmap2, 1024);
rv = bitmap_from_u32array(bmap2, 1024, arr, used_u32s);
expect_eq_uint(used_u32s*32, rv);
/* the 1st nbits of bmap2 are identical to
* bmap1, the remaining bits of bmap2 are cleared
*/
bitmap_zero(bmap1, 1024);
__set_bit(i, bmap1);
expect_eq_bitmap(bmap1, 1024, bmap2, 1024);
/*
* test short conversion bitmap -> u32[] (1
* word too short)
*/
if (used_u32s > 1) {
bitmap_zero(bmap1, 1024);
__set_bit(i, bmap1);
bitmap_set(bmap1, nbits,
1024 - nbits); /* garbage */
memset(arr, 0xff, sizeof(arr));
rv = bitmap_to_u32array(arr, used_u32s - 1,
bmap1, nbits);
expect_eq_uint((used_u32s - 1)*32, rv);
/* 1st used u32 words contain expected
* bit set, the remaining words are
* left unchanged (0xff)
*/
memset(exp_arr, 0xff, sizeof(exp_arr));
memset(exp_arr, 0,
(used_u32s-1)*sizeof(*exp_arr));
if ((i/32) < (used_u32s - 1))
exp_arr[i/32] = (1U<<(i%32));
expect_eq_u32_array(exp_arr, 32, arr, 32);
}
/*
* test short conversion u32[] -> bitmap (3
* bits too short)
*/
if (nbits > 3) {
memset(arr, 0xff, sizeof(arr)); /* garbage */
memset(arr, 0, used_u32s*sizeof(*arr));
arr[i/32] = (1U<<(i%32));
bitmap_zero(bmap1, 1024);
rv = bitmap_from_u32array(bmap1, nbits - 3,
arr, used_u32s);
expect_eq_uint(nbits - 3, rv);
/* we are expecting the bit < nbits -
* 3 (none otherwise), and the rest of
* bmap1 unchanged (0-filled)
*/
bitmap_zero(bmap2, 1024);
if (i < nbits - 3)
__set_bit(i, bmap2);
expect_eq_bitmap(bmap2, 1024, bmap1, 1024);
/* do the same with bmap1 initially
* 1-filled
*/
bitmap_fill(bmap1, 1024);
rv = bitmap_from_u32array(bmap1, nbits - 3,
arr, used_u32s);
expect_eq_uint(nbits - 3, rv);
/* we are expecting the bit < nbits -
* 3 (none otherwise), and the rest of
* bmap1 unchanged (1-filled)
*/
bitmap_zero(bmap2, 1024);
if (i < nbits - 3)
__set_bit(i, bmap2);
bitmap_set(bmap2, nbits-3, 1024 - nbits + 3);
expect_eq_bitmap(bmap2, 1024, bmap1, 1024);
}
}
}
}
static void noinline __init test_mem_optimisations(void)
{
DECLARE_BITMAP(bmap1, 1024);
DECLARE_BITMAP(bmap2, 1024);
unsigned int start, nbits;
for (start = 0; start < 1024; start += 8) {
memset(bmap1, 0x5a, sizeof(bmap1));
memset(bmap2, 0x5a, sizeof(bmap2));
for (nbits = 0; nbits < 1024 - start; nbits += 8) {
bitmap_set(bmap1, start, nbits);
__bitmap_set(bmap2, start, nbits);
if (!bitmap_equal(bmap1, bmap2, 1024))
printk("set not equal %d %d\n", start, nbits);
if (!__bitmap_equal(bmap1, bmap2, 1024))
printk("set not __equal %d %d\n", start, nbits);
bitmap_clear(bmap1, start, nbits);
__bitmap_clear(bmap2, start, nbits);
if (!bitmap_equal(bmap1, bmap2, 1024))
printk("clear not equal %d %d\n", start, nbits);
if (!__bitmap_equal(bmap1, bmap2, 1024))
printk("clear not __equal %d %d\n", start,
nbits);
}
}
}
static int __init test_bitmap_init(void)
{
test_zero_fill_copy();
test_bitmap_u32_array_conversions();
test_mem_optimisations();
if (failed_tests == 0)
pr_info("all %u tests passed\n", total_tests);
else
pr_warn("failed %u out of %u tests\n",
failed_tests, total_tests);
return failed_tests ? -EINVAL : 0;
}
static void __exit test_bitmap_cleanup(void)
{
}
module_init(test_bitmap_init);
module_exit(test_bitmap_cleanup);
MODULE_AUTHOR("david decotigny <david.decotigny@googlers.com>");
MODULE_LICENSE("GPL");
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