8260262: Use common code in function unmap_shared() in perfMemory_posix.cpp #4995

hseigel · 2021-08-04T17:15:46Z

Please review this change to use common code in function unmap_shared() in perfMemory_posix.cpp, to fix JDK-8260262. The change calls munmap() directly to deallocate the memory because functions mmap_create_shared() and mmap_attach_shared() call mmap() directly to allocate the memory.

The change was tested by running Mach5 tiers 1-2 on Linux, MacOS, and Windows, and Mach5 tiers 3-5 on Linux x64 and MacOS x64.

Note that testing on AIX is needed.

Thanks, Harold

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Issue

JDK-8260262: Use common code in function unmap_shared() in perfMemory_posix.cpp

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Thomas Stuefe (@tstuefe - Reviewer)
Coleen Phillimore (@coleenp - Reviewer)

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…ix.cpp

bridgekeeper · 2021-08-04T17:16:45Z

👋 Welcome back hseigel! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2021-08-04T17:19:40Z

@hseigel The following label will be automatically applied to this pull request:

hotspot-runtime

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mlbridge · 2021-08-04T17:23:38Z

Webrevs

00: Full (4860ef8b)

tstuefe

Hi Harold,

thank you for doing this. The patch looks fine to me.

About AIX testing, SAP started to withdraw from AIX development and IBM will take a bigger role in the long run. One of the effects of that decision is that we gave up our AIX CI for OpenJDK head. I still can build and test manually if necessary, but let's first see if IBM has their AIX test systems up yet.

@tellison, could you guys test this or should I do this?

Thank you!

openjdk · 2021-08-09T08:08:58Z

@hseigel This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8260262: Use common code in function unmap_shared() in perfMemory_posix.cpp

Reviewed-by: stuefe, coleenp

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 56 new commits pushed to the master branch:

7fc99cf: 8225488: Examine ExecutableType.getReceiverType behavior when source receiver parameter is absent
4548677: 8268824: Remove unused jdk.accessibility APIs deprecated for removal in JDK 9
b53828b: 8272047: java/nio/channels/FileChannel/Transfer2GPlus.java failed with Unexpected transfer size: 2147418112
41dc795: 8264792: The NumberFormat for locale sq_XK formats price incorrectly.
9c6457f: 8267385: Create NSAccessibilityElement implementation for JavaComponentAccessibility
0ac2be9: 8272123: Problem list 4 jtreg tests which regularly fail on macos-aarch64
272fcb4: 8272113: Build compare script fails with differences in classlist
2f7a469: 8271931: Make AbortVMOnVMOperationTimeout more resilient to OS scheduling
a86ac0d: 8271939: Clean up primitive raw accessors in oopDesc
b84a9c7: 8271956: AArch64: C1 build failed after JDK-8270947
... and 46 more: https://git.openjdk.java.net/jdk/compare/452f7d764fc0112cabf0be944e4233173d63f933...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

coleenp · 2021-08-09T17:17:04Z

src/hotspot/os/posix/perfMemory_posix.cpp

  }
-#else
-  os::release_memory(addr, bytes);


Why doesn't AIX call munmap with os::release_memory() and then do this NMT tracking?

I'm not sure I understand what you are proposing.

The old code was incorrect since it used raw ::mmap() to map perf memory, but used os::release_memory() to release it. This was asymmetric and assumed the underlying implementation for os::reserve/release... uses mmap, which is not always true. The patch corrects this by coupling raw ::mmap with raw ::munmap, and do NMT tracking accordingly.

Arguably, one could factor out mmap+NMT and munmap+NMT in os_posix.cpp. We probably have a number of places where this would be needed. E.g. polling pages and such. But I guess that was out of scope for this issue.

I see, reading the code more ... The code to create the perf memory if PerfDisableSharedMemory=0 used mmap directly so it makes sense to use munmap directly too. This is definitely better.

Aside: This definition is the same on all the posix platforms so could be moved. Not with this RFE but definitely a trivial one.
bool os::pd_unmap_memory(char* addr, size_t bytes) {

coleenp

Looks good.

coleenp · 2021-08-09T19:43:57Z

src/hotspot/os/posix/perfMemory_posix.cpp

  }
-#else
-  os::release_memory(addr, bytes);


I see, reading the code more ... The code to create the perf memory if PerfDisableSharedMemory=0 used mmap directly so it makes sense to use munmap directly too. This is definitely better.

Aside: This definition is the same on all the posix platforms so could be moved. Not with this RFE but definitely a trivial one.
bool os::pd_unmap_memory(char* addr, size_t bytes) {

hseigel · 2021-08-10T12:15:58Z

Thanks Thomas and Coleen for reviewing this change.

/integrate

openjdk · 2021-08-10T12:17:18Z

Going to push as commit 2b05fae.
Since your change was applied there have been 66 commits pushed to the master branch:

f2599ad: 8272196: Remove unused class ParStrongRootsScope
1f88134: 8271869: AArch64: build errors with GCC11 in frame::saved_oop_result
089e83b: 8266490: Extend the OSContainer API to support the pids controller of cgroups
2384e12: 8270098: ZGC: ZBarrierSetC2::clone_at_expansion fails with "Guard against surprises" assert
d53d94b: 8271925: ZGC: Arraycopy stub passes invalid oop to load barrier
3b899ef: 8272168: some hotspot runtime/logging tests don't check exit code
abdc107: 8270454: G1: Simplify region index comparison
eb6f3fe: 8272169: runtime/logging/LoaderConstraintsTest.java doesn't build test.Empty
9654fd7: 8271892: mark hotspot runtime/PrintStringTableStats/PrintStringTableStatsTest.java test as ignoring external VM flags
843943c: 8263567: gtests don't terminate the VM safely
... and 56 more: https://git.openjdk.java.net/jdk/compare/452f7d764fc0112cabf0be944e4233173d63f933...master

Your commit was automatically rebased without conflicts.

openjdk · 2021-08-10T12:17:29Z

@hseigel Pushed as commit 2b05fae.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

8260262: Use common code in function unmap_shared() in perfMemory_pos…

4860ef8

…ix.cpp

openjdk bot added the rfr label Aug 4, 2021

openjdk bot added the hotspot-runtime label Aug 4, 2021

tstuefe approved these changes Aug 9, 2021

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8260262: Use common code in function unmap_shared() in perfMemory_posix.cpp #4995

8260262: Use common code in function unmap_shared() in perfMemory_posix.cpp #4995

hseigel commented Aug 4, 2021 •

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openjdk bot commented Aug 10, 2021

8260262: Use common code in function unmap_shared() in perfMemory_posix.cpp #4995

8260262: Use common code in function unmap_shared() in perfMemory_posix.cpp #4995

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hseigel commented Aug 4, 2021 • edited by openjdk[bot] bot

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