Messages in this thread | | | Date | Thu, 17 Jun 2021 11:02:50 -0700 | From | Nathan Chancellor <> | Subject | Re: [next] [clang] x86_64-linux-gnu-ld: mm/mremap.o: in function `move_pgt_entry': mremap.c:(.text+0x763): undefined reference to `__compiletime_assert_342' |
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Rebuilt the CC list because most people were added based on the incorrect bisect result.
On Thu, Jun 17, 2021 at 02:51:49PM +0100, Matthew Wilcox wrote: > On Thu, Jun 17, 2021 at 06:15:45PM +0530, Naresh Kamboju wrote: > > On Thu, 17 Jun 2021 at 17:41, Naresh Kamboju <naresh.kamboju@linaro.org> wrote: > > > x86_64-linux-gnu-ld: mm/mremap.o: in function `move_pgt_entry': > > > mremap.c:(.text+0x763): undefined reference to `__compiletime_assert_342' > > > > The git bisect pointed out the first bad commit. > > > > The first bad commit: > > commit 928cf6adc7d60c96eca760c05c1000cda061604e > > Author: Stephen Boyd <swboyd@chromium.org> > > Date: Thu Jun 17 15:21:35 2021 +1000 > > module: add printk formats to add module build ID to stacktraces > > Your git bisect probably went astray. There's no way that commit > caused that regression.
My bisect landed on commit 83f85ac75855 ("mm/mremap: convert huge PUD move to separate helper"). flush_pud_tlb_range() evaluates to BUILD_BUG() when CONFIG_TRANSPARENT_HUGEPAGE is unset but this function is present just based on the value of CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD.
$ make -skj(nproc) ARCH=x86_64 CC=clang O=build/x86_64 distclean allnoconfig mm/mremap.o
$ llvm-readelf -s build/x86_64/mm/mremap.o &| rg __compiletime_assert 21: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND __compiletime_assert_337
$ rg TRANSPARENT_ build/x86_64/.config 450:CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE=y 451:CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD=y 562:# CONFIG_TRANSPARENT_HUGEPAGE is not set
Not sure why this does not happen on newer clang versions, presumably something with inlining decisions? Still seems like a legitimate issue to me.
Cheers, Nathan
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