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

[jiefu(傅杰)]

Thanks Ioi for your review.
I will push it later today.

Best regards,
Jie

On 2020/6/15, 1:57 PM, "hotspot-runtime-dev on behalf of Ioi Lam" <hotspot-runtime-dev-bounces at openjdk.java.net on behalf of ioi.lam at oracle.com> wrote:

    Looks good to me, too.
    
    Thanks
    - Ioi
    
    On 6/14/20 4:42 PM, jiefu(傅杰) wrote:
    > Thanks Thomas for your review.
    >
    > May I get a second review for this change?
    >
    > Thanks a lot.
    > Best regards,
    > Jie
    >
    > From: Thomas Stüfe <thomas.stuefe at gmail.com>
    > Date: Sunday, June 14, 2020 at 12:44 AM
    > To: "jiefu(傅杰)" <jiefu at tencent.com>
    > Cc: Hotspot dev runtime <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)
    >
    > Looks good to me. Thanks for fixing it!
    >
    > .. Thomas
    >
    > On Sat, Jun 13, 2020, 17:14 jiefu(傅杰) <jiefu at tencent.com<mailto: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<mailto:thomas.stuefe at gmail.com>>
    > Date: Saturday, June 13, 2020 at 8:41 PM
    > To: "jiefu(傅杰)" <jiefu at tencent.com<mailto:jiefu at tencent.com>>
    > Cc: "hotspot-runtime-dev at openjdk.java.net<mailto:hotspot-runtime-dev at openjdk.java.net>" <hotspot-runtime-dev at openjdk.java.net<mailto: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<mailto: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