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

[Thomas Stüfe]

Looks good to me. Thanks for fixing it!

.. Thomas

On Sat, Jun 13, 2020, 17:14 jiefu(傅杰) <jiefu at tencent.com> wrote:

> Hi Thomas,
>
>
>
> Thanks for your review and nice comments.
>
>
>
> The bug was first found on Linux/x86 machines with our Tencent tlinux OS.
>
>
>
> Updated: http://cr.openjdk.java.net/~jiefu/8247522/webrev.01/
>
>
>
> Your change is really cool.
>
> With your patch, I can even reproduce the bug on our macOS platforms.
>
>
>
> Thanks a lot.
>
> Best regards,
>
> Jie
>
>
>
> *From: *Thomas Stüfe <thomas.stuefe at gmail.com>
> *Date: *Saturday, June 13, 2020 at 8:41 PM
> *To: *"jiefu(傅杰)" <jiefu at tencent.com>
> *Cc: *"hotspot-runtime-dev at openjdk.java.net" <
> hotspot-runtime-dev at openjdk.java.net>
> *Subject: *Re: RFR: 8247522: assert(is_aligned(class_space_rs.base(),
> class_space_alignment)) failed: Sanity(Internet mail)
>
>
>
> 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
>
>