RFR: 8247522: assert(is_aligned(class_space_rs.base(), class_space_alignment)) failed: Sanity

[Thomas Stüfe]

Hi Jie,

good catch! What platform did this occur on?

Please remove the casts, you do not need them.

Please add the following lines to your patch - these test modifications
trigger the bug also on linux x64:

---------------

diff -r 19b3969274ce test/hotspot/jtreg/runtime/cds/SharedBaseAddress.java
--- a/test/hotspot/jtreg/runtime/cds/SharedBaseAddress.java     Thu Jun 11
12:51:09 2020 +0200
+++ b/test/hotspot/jtreg/runtime/cds/SharedBaseAddress.java     Sat Jun 13
14:36:46 2020 +0200
@@ -41,6 +41,7 @@
         "1g", "8g", "64g","512g", "4t",
         "32t", "128t", "0",
         "1", "64k", "64M",
+        "0x800001000",        // Default base address + 1 page - probably
valid but unaligned to metaspace alignment, see JDK 8247522
         "0xfffffffffff00000", // archive top wraps around 64-bit address
space
         "0xfff80000",         // archive top wraps around 32-bit address
space
         "0xffffffffffffffff", // archive bottom wraps around 64-bit
address space -- due to align_up()
diff -r 19b3969274ce
test/hotspot/jtreg/runtime/cds/appcds/SharedBaseAddress.java
--- a/test/hotspot/jtreg/runtime/cds/appcds/SharedBaseAddress.java      Thu
Jun 11 12:51:09 2020 +0200
+++ b/test/hotspot/jtreg/runtime/cds/appcds/SharedBaseAddress.java      Sat
Jun 13 14:36:46 2020 +0200
@@ -41,7 +41,8 @@
     private static final String[] testTable = {
         "1g", "8g", "64g","512g", "4t",
         "32t", "128t", "0",
-        "1", "64k", "64M", "320g"
+        "1", "64k", "64M", "320g",
+        "0x800001000"  // Default base address + 1 page - probably valid
but unaligned to metaspace alignment, see JDK 8247522
     };

     public static void main(String[] args) throws Exception {

---------------

Thanks, Thomas


On Sat, Jun 13, 2020 at 11:44 AM jiefu(傅杰) <jiefu at tencent.com> wrote:

> Hi all,
>
> JBS:    https://bugs.openjdk.java.net/browse/JDK-8247522
> Webrev: http://cr.openjdk.java.net/~jiefu/8247522/webrev.00/
>
> This bug was triggered after JDK-8245707.
> The reason is that ccs_begin_offset[1] is incorrect when
> archive_space_alignment != class_space_alignment.
>
> Before JDK-8245707, archive_space_alignment = class_space_alignment = 4k.
> After JDK-8245707,  archive_space_alignment = 4k, class_space_alignment =
> 16k.
>
> When the assert happened, we had observed base_address[2] = 4096, which is
> unaligned to class_space_alignment=16k.
>
> - Testing:
>          tier1 on Linux/x64
>
> Thanks a lot.
> Best regards,
> Jie
>
> [1]
> http://hg.openjdk.java.net/jdk/jdk15/file/1c81917f228b/src/hotspot/share/memory/metaspaceShared.cpp#l2505
> [2]
> http://hg.openjdk.java.net/jdk/jdk15/file/1c81917f228b/src/hotspot/share/memory/metaspaceShared.cpp#l2514
>