Add unit test of ext4_mb_generate_buddy
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
---
fs/ext4/mballoc-test.c | 207 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 207 insertions(+)
diff --git a/fs/ext4/mballoc-test.c b/fs/ext4/mballoc-test.c
index 3aac42ea6..6964974fa 100644
--- a/fs/ext4/mballoc-test.c
+++ b/fs/ext4/mballoc-test.c
@@ -28,6 +28,50 @@ struct mbt_ext4_super_block {
#define MBT_CTX(_sb) (&(container_of((_sb), struct mbt_ext4_super_block, sb)->mbt_ctx))
#define MBT_GRP_CTX(_sb, _group) (&MBT_CTX(_sb)->grp_ctx[_group])
+static const struct super_operations mbt_sops = {
+};
+
+static int mbt_mb_init(struct super_block *sb)
+{
+ int ret;
+
+ /* needed by ext4_mb_init->bdev_nonrot(sb->s_bdev) */
+ sb->s_bdev = kzalloc(sizeof(*sb->s_bdev), GFP_KERNEL);
+ if (sb->s_bdev == NULL)
+ return -ENOMEM;
+
+ sb->s_bdev->bd_queue = kzalloc(sizeof(struct request_queue), GFP_KERNEL);
+ if (sb->s_bdev->bd_queue == NULL) {
+ kfree(sb->s_bdev);
+ return -ENOMEM;
+ }
+
+ /*
+ * needed by ext4_mb_init->ext4_mb_init_backend-> sbi->s_buddy_cache =
+ * new_inode(sb);
+ */
+ INIT_LIST_HEAD(&sb->s_inodes);
+ sb->s_op = &mbt_sops;
+
+ ret = ext4_mb_init(sb);
+ if (ret != 0)
+ goto err_out;
+
+ return 0;
+
+err_out:
+ kfree(sb->s_bdev->bd_queue);
+ kfree(sb->s_bdev);
+ return ret;
+}
+
+static void mbt_mb_release(struct super_block *sb)
+{
+ ext4_mb_release(sb);
+ kfree(sb->s_bdev->bd_queue);
+ kfree(sb->s_bdev);
+}
+
static struct super_block *mbt_ext4_alloc_super_block(void)
{
struct ext4_super_block *es = kzalloc(sizeof(*es), GFP_KERNEL);
@@ -37,8 +81,16 @@ static struct super_block *mbt_ext4_alloc_super_block(void)
if (fsb == NULL || sbi == NULL || es == NULL)
goto out;
+ sbi->s_blockgroup_lock =
+ kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL);
+ if (!sbi->s_blockgroup_lock)
+ goto out;
+
+ bgl_lock_init(sbi->s_blockgroup_lock);
+
sbi->s_es = es;
fsb->sb.s_fs_info = sbi;
+
return &fsb->sb;
out:
@@ -54,6 +106,7 @@ static void mbt_ext4_free_super_block(struct super_block *sb)
container_of(sb, struct mbt_ext4_super_block, sb);
struct ext4_sb_info *sbi = EXT4_SB(sb);
+ kfree(sbi->s_blockgroup_lock);
kfree(sbi->s_es);
kfree(sbi);
kfree(fsb);
@@ -83,6 +136,9 @@ static void mbt_init_sb_layout(struct super_block *sb,
sbi->s_clusters_per_group = layout->blocks_per_group >>
layout->cluster_bits;
sbi->s_desc_size = layout->desc_size;
+ sbi->s_desc_per_block_bits =
+ sb->s_blocksize_bits - (fls(layout->desc_size) - 1);
+ sbi->s_desc_per_block = 1 << sbi->s_desc_per_block_bits;
es->s_first_data_block = cpu_to_le32(0);
es->s_blocks_count_lo = cpu_to_le32(layout->blocks_per_group *
@@ -240,6 +296,14 @@ static int mbt_kunit_init(struct kunit *test)
kunit_activate_static_stub(test,
ext4_mb_mark_context,
ext4_mb_mark_context_stub);
+
+ /* stub function will be called in mt_mb_init->ext4_mb_init */
+ if (mbt_mb_init(sb) != 0) {
+ mbt_ctx_release(sb);
+ mbt_ext4_free_super_block(sb);
+ return -ENOMEM;
+ }
+
return 0;
}
@@ -247,6 +311,7 @@ static void mbt_kunit_exit(struct kunit *test)
{
struct super_block *sb = (struct super_block *)test->priv;
+ mbt_mb_release(sb);
mbt_ctx_release(sb);
mbt_ext4_free_super_block(sb);
}
@@ -392,6 +457,147 @@ static void test_free_blocks_simple(struct kunit *test)
ranges[i].start, ranges[i].len);
}
+static void mbt_generate_buddy(struct super_block *sb, void *buddy,
+ void *bitmap, struct ext4_group_info *grp)
+{
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ uint32_t order, off;
+ void *bb, *bb_h;
+ int max;
+
+ memset(buddy, 0xff, sb->s_blocksize);
+ memset(grp, 0, offsetof(struct ext4_group_info,
+ bb_counters[MB_NUM_ORDERS(sb)]));
+
+ bb = bitmap;
+ max = EXT4_CLUSTERS_PER_GROUP(sb);
+ bb_h = buddy + sbi->s_mb_offsets[1];
+
+ off = mb_find_next_zero_bit(bb, max, 0);
+ grp->bb_first_free = off;
+ while (off < max) {
+ grp->bb_counters[0]++;
+ grp->bb_free++;
+
+ if (!(off & 1) && !mb_test_bit(off + 1, bb)) {
+ grp->bb_free++;
+ grp->bb_counters[0]--;
+ mb_clear_bit(off >> 1, bb_h);
+ grp->bb_counters[1]++;
+ grp->bb_largest_free_order = 1;
+ off++;
+ }
+
+ off = mb_find_next_zero_bit(bb, max, off + 1);
+ }
+
+ for (order = 1; order < MB_NUM_ORDERS(sb) - 1; order++) {
+ bb = buddy + sbi->s_mb_offsets[order];
+ bb_h = buddy + sbi->s_mb_offsets[order + 1];
+ max = max >> 1;
+ off = mb_find_next_zero_bit(bb, max, 0);
+
+ while (off < max) {
+ if (!(off & 1) && !mb_test_bit(off + 1, bb)) {
+ mb_set_bits(bb, off, 2);
+ grp->bb_counters[order] -= 2;
+ mb_clear_bit(off >> 1, bb_h);
+ grp->bb_counters[order + 1]++;
+ grp->bb_largest_free_order = order + 1;
+ off++;
+ }
+
+ off = mb_find_next_zero_bit(bb, max, off + 1);
+ }
+ }
+
+ max = EXT4_CLUSTERS_PER_GROUP(sb);
+ off = mb_find_next_zero_bit(bitmap, max, 0);
+ while (off < max) {
+ grp->bb_fragments++;
+
+ off = mb_find_next_bit(bitmap, max, off + 1);
+ if (off + 1 >= max)
+ break;
+
+ off = mb_find_next_zero_bit(bitmap, max, off + 1);
+ }
+}
+
+static void
+mbt_validate_group_info(struct kunit *test, struct ext4_group_info *grp1,
+ struct ext4_group_info *grp2)
+{
+ struct super_block *sb = (struct super_block *)test->priv;
+ int i;
+
+ KUNIT_ASSERT_EQ(test, grp1->bb_first_free,
+ grp2->bb_first_free);
+ KUNIT_ASSERT_EQ(test, grp1->bb_fragments,
+ grp2->bb_fragments);
+ KUNIT_ASSERT_EQ(test, grp1->bb_free, grp2->bb_free);
+ KUNIT_ASSERT_EQ(test, grp1->bb_largest_free_order,
+ grp2->bb_largest_free_order);
+
+ for (i = 1; i < MB_NUM_ORDERS(sb); i++) {
+ KUNIT_ASSERT_EQ_MSG(test, grp1->bb_counters[i],
+ grp2->bb_counters[i],
+ "bb_counters[%d] diffs, expected %d, generated %d",
+ i, grp1->bb_counters[i],
+ grp2->bb_counters[i]);
+ }
+}
+
+static void
+do_test_generate_buddy(struct kunit *test, struct super_block *sb, void *bitmap,
+ void *mbt_buddy, struct ext4_group_info *mbt_grp,
+ void *ext4_buddy, struct ext4_group_info *ext4_grp)
+{
+ int i;
+
+ mbt_generate_buddy(sb, mbt_buddy, bitmap, mbt_grp);
+
+ for (i = 0; i < MB_NUM_ORDERS(sb); i++)
+ ext4_grp->bb_counters[i] = 0;
+ /* needed by validation in ext4_mb_generate_buddy */
+ ext4_grp->bb_free = mbt_grp->bb_free;
+ memset(ext4_buddy, 0xff, sb->s_blocksize);
+ ext4_mb_generate_buddy(sb, ext4_buddy, bitmap, TEST_GOAL_GROUP,
+ ext4_grp);
+
+ KUNIT_ASSERT_EQ(test, memcmp(mbt_buddy, ext4_buddy, sb->s_blocksize),
+ 0);
+ mbt_validate_group_info(test, mbt_grp, ext4_grp);
+}
+
+static void test_mb_generate_buddy(struct kunit *test)
+{
+ struct super_block *sb = (struct super_block *)test->priv;
+ void *bitmap, *expected_bb, *generate_bb;
+ struct ext4_group_info *expected_grp, *generate_grp;
+ struct test_range ranges[TEST_RANGE_COUNT];
+ int i;
+
+ bitmap = kunit_kzalloc(test, sb->s_blocksize, GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bitmap);
+ expected_bb = kunit_kzalloc(test, sb->s_blocksize, GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, expected_bb);
+ generate_bb = kunit_kzalloc(test, sb->s_blocksize, GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, generate_bb);
+ expected_grp = kunit_kzalloc(test, offsetof(struct ext4_group_info,
+ bb_counters[MB_NUM_ORDERS(sb)]), GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, expected_grp);
+ generate_grp = ext4_get_group_info(sb, TEST_GOAL_GROUP);
+ KUNIT_ASSERT_NOT_NULL(test, generate_grp);
+
+ mbt_generate_test_ranges(sb, ranges, TEST_RANGE_COUNT);
+ for (i = 0; i < TEST_RANGE_COUNT; i++) {
+ mb_set_bits(bitmap, ranges[i].start, ranges[i].len);
+ do_test_generate_buddy(test, sb, bitmap, expected_bb,
+ expected_grp, generate_bb, generate_grp);
+ }
+}
+
static const struct mbt_ext4_block_layout mbt_test_layouts[] = {
{
.blocksize_bits = 10,
@@ -430,6 +636,7 @@ KUNIT_ARRAY_PARAM(mbt_layouts, mbt_test_layouts, mbt_show_layout);
static struct kunit_case mbt_test_cases[] = {
KUNIT_CASE_PARAM(test_new_blocks_simple, mbt_layouts_gen_params),
KUNIT_CASE_PARAM(test_free_blocks_simple, mbt_layouts_gen_params),
+ KUNIT_CASE_PARAM(test_mb_generate_buddy, mbt_layouts_gen_params),
{}
};
--
2.30.0Hi, On Wed, Jan 03, 2024 at 06:48:57PM +0800, Kemeng Shi wrote: > Add unit test of ext4_mb_generate_buddy > > Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> With this and other new ext4 tests test in the tree, I see a variety of backtraces in the upstream kernel if debug options are enabled. An example is [ 6.821447] KTAP version 1 [ 6.821769] # Subtest: test_mb_generate_buddy [ 6.824787] ============================================================================= [ 6.825568] BUG inode_cache (Tainted: G N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 ... [ 6.894341] ok 7 ext4_inode_test [ 6.895411] ============================================================================= [ 6.895777] BUG inode_cache (Tainted: G B N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 Another example, from another test run, is [ 3.938551] # Subtest: test_new_blocks_simple [ 3.947171] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 [ 3.952988] ok 2 block_bits=12 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 [ 3.958403] ok 3 block_bits=16 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 [ 3.958890] ============================================================================= [ 3.959159] BUG inode_cache (Tainted: G N): Padding overwritten. 0xffff8de881adbf68-0xffff8de881adbf6f @offset=16232 Another one: [ 18.730473] # Subtest: test_new_blocks_simple [ 18.760547] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 [ 18.778477] ================================================================== [ 18.778950] BUG: KFENCE: out-of-bounds write in ext4_mb_init+0x5d7/0xa60 This is just a sample, taken from a quick look at test results. Are those backtraces expected ? If so, would it be possible to execute the tests without generating such backtraces ? The backtraces, if intentional, hide real problems in the noise. Thanks, Guenter
on 3/21/2024 12:23 AM, Guenter Roeck wrote: > Hi, > > On Wed, Jan 03, 2024 at 06:48:57PM +0800, Kemeng Shi wrote: >> Add unit test of ext4_mb_generate_buddy >> >> Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> > > With this and other new ext4 tests test in the tree, I see a variety > of backtraces in the upstream kernel if debug options are enabled. > An example is > > [ 6.821447] KTAP version 1 > [ 6.821769] # Subtest: test_mb_generate_buddy > [ 6.824787] ============================================================================= > [ 6.825568] BUG inode_cache (Tainted: G N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 > ... > [ 6.894341] ok 7 ext4_inode_test > [ 6.895411] ============================================================================= > [ 6.895777] BUG inode_cache (Tainted: G B N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 > > Another example, from another test run, is > > [ 3.938551] # Subtest: test_new_blocks_simple > [ 3.947171] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 > [ 3.952988] ok 2 block_bits=12 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 > [ 3.958403] ok 3 block_bits=16 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 > [ 3.958890] ============================================================================= > [ 3.959159] BUG inode_cache (Tainted: G N): Padding overwritten. 0xffff8de881adbf68-0xffff8de881adbf6f @offset=16232 > > Another one: > > [ 18.730473] # Subtest: test_new_blocks_simple > [ 18.760547] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 > [ 18.778477] ================================================================== > [ 18.778950] BUG: KFENCE: out-of-bounds write in ext4_mb_init+0x5d7/0xa60 > > This is just a sample, taken from a quick look at test results. > > Are those backtraces expected ? If so, would it be possible to execute the > tests without generating such backtraces ? The backtraces, if intentional, > hide real problems in the noise. Thanks for the report. The backtrace is not expected, I will look into this. Thansk! > > Thanks, > Guenter >
on 3/21/2024 3:16 PM, Kemeng Shi wrote: > > > on 3/21/2024 12:23 AM, Guenter Roeck wrote: >> Hi, >> >> On Wed, Jan 03, 2024 at 06:48:57PM +0800, Kemeng Shi wrote: >>> Add unit test of ext4_mb_generate_buddy >>> >>> Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> >> >> With this and other new ext4 tests test in the tree, I see a variety >> of backtraces in the upstream kernel if debug options are enabled. >> An example is >> >> [ 6.821447] KTAP version 1 >> [ 6.821769] # Subtest: test_mb_generate_buddy >> [ 6.824787] ============================================================================= >> [ 6.825568] BUG inode_cache (Tainted: G N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 >> ... >> [ 6.894341] ok 7 ext4_inode_test >> [ 6.895411] ============================================================================= >> [ 6.895777] BUG inode_cache (Tainted: G B N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 >> >> Another example, from another test run, is >> >> [ 3.938551] # Subtest: test_new_blocks_simple >> [ 3.947171] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >> [ 3.952988] ok 2 block_bits=12 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >> [ 3.958403] ok 3 block_bits=16 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >> [ 3.958890] ============================================================================= >> [ 3.959159] BUG inode_cache (Tainted: G N): Padding overwritten. 0xffff8de881adbf68-0xffff8de881adbf6f @offset=16232 >> >> Another one: >> >> [ 18.730473] # Subtest: test_new_blocks_simple >> [ 18.760547] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >> [ 18.778477] ================================================================== >> [ 18.778950] BUG: KFENCE: out-of-bounds write in ext4_mb_init+0x5d7/0xa60 >> >> This is just a sample, taken from a quick look at test results. >> >> Are those backtraces expected ? If so, would it be possible to execute the >> tests without generating such backtraces ? The backtraces, if intentional, >> hide real problems in the noise. > Thanks for the report. The backtrace is not expected, I will look into this. Thansk! >> Hi Guenter, I could not reproduce this in my local vm. From the reported backtraces, it's likely there is a out-of-bounds write to sbi->s_buddy_cache. I try to fix this in [1] and it works fine in my local vm. I wish this work for you to elimate the reported nosie. Look forward to your reply, Thanks. Kemeng [1] https://lore.kernel.org/linux-ext4/20240322165518.8147-1-shikemeng@huaweicloud.com/T/#u >> Thanks, >> Guenter >>
On 3/22/24 02:27, Kemeng Shi wrote: > > > on 3/21/2024 3:16 PM, Kemeng Shi wrote: >> >> >> on 3/21/2024 12:23 AM, Guenter Roeck wrote: >>> Hi, >>> >>> On Wed, Jan 03, 2024 at 06:48:57PM +0800, Kemeng Shi wrote: >>>> Add unit test of ext4_mb_generate_buddy >>>> >>>> Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> >>> >>> With this and other new ext4 tests test in the tree, I see a variety >>> of backtraces in the upstream kernel if debug options are enabled. >>> An example is >>> >>> [ 6.821447] KTAP version 1 >>> [ 6.821769] # Subtest: test_mb_generate_buddy >>> [ 6.824787] ============================================================================= >>> [ 6.825568] BUG inode_cache (Tainted: G N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 >>> ... >>> [ 6.894341] ok 7 ext4_inode_test >>> [ 6.895411] ============================================================================= >>> [ 6.895777] BUG inode_cache (Tainted: G B N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 >>> >>> Another example, from another test run, is >>> >>> [ 3.938551] # Subtest: test_new_blocks_simple >>> [ 3.947171] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >>> [ 3.952988] ok 2 block_bits=12 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >>> [ 3.958403] ok 3 block_bits=16 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >>> [ 3.958890] ============================================================================= >>> [ 3.959159] BUG inode_cache (Tainted: G N): Padding overwritten. 0xffff8de881adbf68-0xffff8de881adbf6f @offset=16232 >>> >>> Another one: >>> >>> [ 18.730473] # Subtest: test_new_blocks_simple >>> [ 18.760547] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >>> [ 18.778477] ================================================================== >>> [ 18.778950] BUG: KFENCE: out-of-bounds write in ext4_mb_init+0x5d7/0xa60 >>> >>> This is just a sample, taken from a quick look at test results. >>> >>> Are those backtraces expected ? If so, would it be possible to execute the >>> tests without generating such backtraces ? The backtraces, if intentional, >>> hide real problems in the noise. >> Thanks for the report. The backtrace is not expected, I will look into this. Thansk! >>> > Hi Guenter, I could not reproduce this in my local vm. From the reported backtraces, it's > likely there is a out-of-bounds write to sbi->s_buddy_cache. I try to fix this in [1] and > it works fine in my local vm. I wish this work for you to elimate the reported nosie. > Look forward to your reply, Thanks. > You would need to have CONFIG_SLUB_DEBUG=y, CONFIG_SLUB_DEBUG_ON=y, and CONFIG_KFENCE=y to see the problems. Guenter
on 3/22/2024 10:49 PM, Guenter Roeck wrote: > On 3/22/24 02:27, Kemeng Shi wrote: >> >> >> on 3/21/2024 3:16 PM, Kemeng Shi wrote: >>> >>> >>> on 3/21/2024 12:23 AM, Guenter Roeck wrote: >>>> Hi, >>>> >>>> On Wed, Jan 03, 2024 at 06:48:57PM +0800, Kemeng Shi wrote: >>>>> Add unit test of ext4_mb_generate_buddy >>>>> >>>>> Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> >>>> >>>> With this and other new ext4 tests test in the tree, I see a variety >>>> of backtraces in the upstream kernel if debug options are enabled. >>>> An example is >>>> >>>> [ 6.821447] KTAP version 1 >>>> [ 6.821769] # Subtest: test_mb_generate_buddy >>>> [ 6.824787] ============================================================================= >>>> [ 6.825568] BUG inode_cache (Tainted: G N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 >>>> ... >>>> [ 6.894341] ok 7 ext4_inode_test >>>> [ 6.895411] ============================================================================= >>>> [ 6.895777] BUG inode_cache (Tainted: G B N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 >>>> >>>> Another example, from another test run, is >>>> >>>> [ 3.938551] # Subtest: test_new_blocks_simple >>>> [ 3.947171] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >>>> [ 3.952988] ok 2 block_bits=12 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >>>> [ 3.958403] ok 3 block_bits=16 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >>>> [ 3.958890] ============================================================================= >>>> [ 3.959159] BUG inode_cache (Tainted: G N): Padding overwritten. 0xffff8de881adbf68-0xffff8de881adbf6f @offset=16232 >>>> >>>> Another one: >>>> >>>> [ 18.730473] # Subtest: test_new_blocks_simple >>>> [ 18.760547] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 >>>> [ 18.778477] ================================================================== >>>> [ 18.778950] BUG: KFENCE: out-of-bounds write in ext4_mb_init+0x5d7/0xa60 >>>> >>>> This is just a sample, taken from a quick look at test results. >>>> >>>> Are those backtraces expected ? If so, would it be possible to execute the >>>> tests without generating such backtraces ? The backtraces, if intentional, >>>> hide real problems in the noise. >>> Thanks for the report. The backtrace is not expected, I will look into this. Thansk! >>>> >> Hi Guenter, I could not reproduce this in my local vm. From the reported backtraces, it's >> likely there is a out-of-bounds write to sbi->s_buddy_cache. I try to fix this in [1] and >> it works fine in my local vm. I wish this work for you to elimate the reported nosie. >> Look forward to your reply, Thanks. >> > > You would need to have CONFIG_SLUB_DEBUG=y, CONFIG_SLUB_DEBUG_ON=y, and CONFIG_KFENCE=y > to see the problems. Thanks for sharing this. I have already turn these configs on, but I use the ext4 tree https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git/log/?h=dev which may be the reason why I can't reproduce the issue. I see you have already tested the fix in upstream. Thanks a lot for that! Kemeng > > Guenter >
[ Adding more interested parties] On Wed, Mar 20, 2024 at 09:23:24AM -0700, Guenter Roeck wrote: > Hi, > > On Wed, Jan 03, 2024 at 06:48:57PM +0800, Kemeng Shi wrote: > > Add unit test of ext4_mb_generate_buddy > > > > Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> > > With this and other new ext4 tests test in the tree, I see a variety > of backtraces in the upstream kernel if debug options are enabled. > An example is > > [ 6.821447] KTAP version 1 > [ 6.821769] # Subtest: test_mb_generate_buddy > [ 6.824787] ============================================================================= > [ 6.825568] BUG inode_cache (Tainted: G N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 > ... > [ 6.894341] ok 7 ext4_inode_test > [ 6.895411] ============================================================================= > [ 6.895777] BUG inode_cache (Tainted: G B N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232 > > Another example, from another test run, is > > [ 3.938551] # Subtest: test_new_blocks_simple > [ 3.947171] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 > [ 3.952988] ok 2 block_bits=12 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 > [ 3.958403] ok 3 block_bits=16 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 > [ 3.958890] ============================================================================= > [ 3.959159] BUG inode_cache (Tainted: G N): Padding overwritten. 0xffff8de881adbf68-0xffff8de881adbf6f @offset=16232 > > Another one: > > [ 18.730473] # Subtest: test_new_blocks_simple > [ 18.760547] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64 > [ 18.778477] ================================================================== > [ 18.778950] BUG: KFENCE: out-of-bounds write in ext4_mb_init+0x5d7/0xa60 > > This is just a sample, taken from a quick look at test results. > > Are those backtraces expected ? If so, would it be possible to execute the > tests without generating such backtraces ? The backtraces, if intentional, > hide real problems in the noise. > > Thanks, > Guenter
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