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

[Thomas Stüfe]

Will you push it to head, then downport it to 15?

For that matter, how does this even work currently?

On Mon, Jun 15, 2020 at 8:22 AM jiefu(傅杰) <jiefu at tencent.com> wrote:

> 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
>
>
>
>
>