Re: [dhowells-fs:netfs-folio-regions 11/28] fs/netfs/read_helper.c:979:13: warning: variable 'folio' is uninitialized when used here

From: Nathan Chancellor
Date: Thu Aug 19 2021 - 15:59:12 EST

On Fri, Aug 20, 2021 at 03:07:06AM +0800, kernel test robot wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git netfs-folio-regions
> head: 215a4ee495a95cc73256ed76f91cb78bcabd6b8e
> commit: 90417b52931da8cb4eb670c3cc22bfa12aabe55c [11/28] netfs: Use a buffer in netfs_read_request and add pages to it
> config: hexagon-randconfig-r041-20210818 (attached as .config)
> compiler: clang version 12.0.0
> reproduce (this is a W=1 build):
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit/?id=90417b52931da8cb4eb670c3cc22bfa12aabe55c
> git remote add dhowells-fs https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git
> git fetch --no-tags dhowells-fs netfs-folio-regions
> git checkout 90417b52931da8cb4eb670c3cc22bfa12aabe55c
> # save the attached .config to linux build tree
> mkdir build_dir
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross O=build_dir ARCH=hexagon SHELL=/bin/bash fs/netfs/
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>
> All warnings (new ones prefixed by >>):
>
> >> fs/netfs/read_helper.c:979:13: warning: variable 'folio' is uninitialized when used here
> folio_get(folio);
> ^~~~~
> fs/netfs/read_helper.c:932:21: note: initialize the variable 'folio' to silence this warning
> struct folio
> ^
> = NULL
> fatal error: error in backend: Misaligned constant address: 0x0000001b has alignment 1, but the memory access requires 4

This crash has been fixed in clang-13 [1]. Philip, would it be possible for
the robot to use the same clang version for Hexagon that you use for all of the
other architectures? It should have no issues, as we are using it in our
CI. If there are, please let me know so I can try to get them triaged
and fixed upstream,

[1] https://bugs.llvm.org/show_bug.cgi?id=50838

Cheers,
Nathan

> PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script.
> Stack dump:
> 0. Program arguments: clang -Wp,-MMD,fs/netfs/.read_helper.o.d -nostdinc -isystem /opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/lib/clang/12.0.0/include -Iarch/hexagon/include -I./arch/hexagon/include/generated -Iinclude -I./include -Iarch/hexagon/include/uapi -I./arch/hexagon/include/generated/uapi -Iinclude/uapi -I./include/generated/uapi -include include/linux/compiler-version.h -include include/linux/kconfig.h -include include/linux/compiler_types.h -D__KERNEL__ -Qunused-arguments -fmacro-prefix-map== -DKBUILD_EXTRA_WARN1 -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration -Werror=implicit-int -Werror=return-type -Wno-format-security -std=gnu89 --target=hexagon-unknown-linux-musl -integrated-as -Werror=unknown-warning-option -G0 -fno-short-enums -mlong-calls -ffixed-r19 -DTHREADINFO_REG=r19 -D__linux__ -fno-delete-null-pointer-checks -Wno-frame-address -Wno-address-of-packed-member -O2 -Wframe-larger-than=1024 -fno-stack-protector -Wno-format-invalid-specifier -Wno-gnu -mno-global-merge -Wno-unused-const-variable -fno-omit-frame-pointer -fno-optimize-sibling-calls -ftrivial-auto-var-init=pattern -fno-stack-clash-protection -falign-functions=64 -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -Wno-array-bounds -fno-strict-overflow -fno-stack-check -Werror=date-time -Werror=incompatible-pointer-types -Wextra -Wunused -Wno-unused-parameter -Wmissing-declarations -Wmissing-format-attribute -Wmissing-prototypes -Wold-style-definition -Wmissing-include-dirs -Wunused-const-variable -Wno-missing-field-initializers -Wno-sign-compare -Wno-type-limits -I fs/netfs -I ./fs/netfs -DKBUILD_MODFILE="fs/netfs/netfs" -DKBUILD_BASENAME="read_helper" -DKBUILD_MODNAME="netfs" -D__KBUILD_MODNAME=kmod_netfs -c -o fs/netfs/read_helper.o fs/netfs/read_helper.c
> 1. <eof> parser at end of file
> 2. Code generation
> 3. Running pass 'Function Pass Manager' on module 'fs/netfs/read_helper.c'.
> 4. Running pass 'Hexagon DAG->DAG Pattern Instruction Selection' on function '@netfs_rreq_set_up_buffer'
> #0 0x000000000355d1fc llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x355d1fc)
> #1 0x000000000355afbe llvm::sys::RunSignalHandlers() (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x355afbe)
> #2 0x000000000355c55d llvm::sys::CleanupOnSignal(unsigned long) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x355c55d)
> #3 0x00000000034d5aed (anonymous namespace)::CrashRecoveryContextImpl::HandleCrash(int, unsigned long) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x34d5aed)
> #4 0x00000000034d5a79 llvm::CrashRecoveryContext::HandleExit(int) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x34d5a79)
> #5 0x0000000003557e07 llvm::sys::Process::Exit(int, bool) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x3557e07)
> #6 0x0000000002107e10 llvm::DenseMapBase<llvm::DenseMap<llvm::AliasSetTracker::ASTCallbackVH, llvm::AliasSetTracker::ASTCallbackVHDenseMapInfo, llvm::detail::DenseMapPair<llvm::AliasSetTracker::ASTCallbackVH, >, llvm::AliasSetTracker::ASTCallbackVH, llvm::AliasSetTracker::ASTCallbackVHDenseMapInfo, llvm::detail::DenseMapPair<llvm::AliasSetTracker::ASTCallbackVH, >::destroyAll() (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x2107e10)
> #7 0x00000000034da319 llvm::report_fatal_error(llvm::Twine const&, bool) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x34da319)
> #8 0x00000000034da3e7 (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x34da3e7)
> #9 0x0000000002411b46 (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x2411b46)
> #10 0x00000000024183c0 llvm::HexagonTargetLowering::LowerLoad(llvm::SDValue, llvm::SelectionDAG&) const (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x24183c0)
> #11 0x0000000002419cbb llvm::HexagonTargetLowering::LowerOperation(llvm::SDValue, llvm::SelectionDAG&) const (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x2419cbb)
> #12 0x00000000042c3b6a (anonymous (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x42c3b6a)
> #13 0x00000000042a61af (anonymous (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x42a61af)
> #14 0x00000000042a5443 llvm::SelectionDAG::Legalize() (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x42a5443)
> #15 0x0000000004375361 llvm::SelectionDAGISel::CodeGenAndEmitDAG() (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x4375361)
> #16 0x0000000004373545 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x4373545)
> #17 0x00000000043703b7 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x43703b7)
> #18 0x00000000024690c4 llvm::HexagonDAGToDAGISel::runOnMachineFunction(llvm::MachineFunction&) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x24690c4)
> #19 0x000000000290c1bd llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x290c1bd)
> #20 0x0000000002d6a745 llvm::FPPassManager::runOnFunction(llvm::Function&) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x2d6a745)
> #21 0x0000000002d70c51 llvm::FPPassManager::runOnModule(llvm::Module&) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x2d70c51)
> #22 0x0000000002d6adaa llvm::legacy::PassManagerImpl::run(llvm::Module&) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x2d6adaa)
> #23 0x000000000378e9a0 clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, llvm::DataLayout const&, clang::BackendAction, std::__1::unique_ptr<llvm::raw_pwrite_stream, std::__1::default_delete<llvm::raw_pwrite_stream> >) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x378e9a0)
> #24 0x0000000003ebec56 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x3ebec56)
> #25 0x0000000004dbbc84 clang::ParseAST(clang::Sema&, bool, bool) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x4dbbc84)
> #26 0x0000000003e0d560 clang::FrontendAction::Execute() (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x3e0d560)
> #27 0x0000000003d596da clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x3d596da)
> #28 0x0000000003eb890e (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x3eb890e)
> #29 0x0000000002107abe cc1_main(llvm::ArrayRef<char char (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x2107abe)
> #30 0x00000000021054ee ExecuteCC1Tool(llvm::SmallVectorImpl<char (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x21054ee)
> #31 0x0000000003c04bd2 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef> >, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> const::$_1>(long) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x3c04bd2)
> #32 0x00000000034d5a2b llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x34d5a2b)
> #33 0x0000000003c043c5 clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef> >, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> const (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x3c043c5)
> #34 0x0000000003bcc196 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x3bcc196)
> #35 0x0000000003bcc617 clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::__1::pair<int, clang::driver::Command >&) const (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x3bcc617)
> #36 0x0000000003be5a81 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::__1::pair<int, clang::driver::Command >&) (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x3be5a81)
> #37 0x0000000002104e21 main (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x2104e21)
> #38 0x00007f04bb011d0a __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x26d0a)
> #39 0x0000000002102299 _start (/opt/cross/clang+llvm-12.0.0-cross-hexagon-unknown-linux-musl/x86_64-linux-gnu/bin/clang-12+0x2102299)
> clang-12: error: clang frontend command failed with exit code 70 (use -v to see invocation)
> clang version 12.0.0
> Target: hexagon-unknown-linux-musl
> Thread model: posix
> InstalledDir: /opt/cross/clang_hexagon/x86_64-linux-gnu/bin
> clang-12: note: diagnostic msg:
> Makefile arch fs include kernel nr_bisected scripts source usr
>
>
> vim +/folio +979 fs/netfs/read_helper.c
>
> 947
> 948 ret = netfs_rreq_add_folios_to_buffer(rreq, want_index, have_index - 1,
> 949 gfp_mask);
> 950 if (ret < 0)
> 951 return ret;
> 952 have_folios += have_index - want_index;
> 953
> 954 ret = netfs_rreq_add_folios_to_buffer(rreq, have_index + have_folios,
> 955 want_index + want_folios - 1,
> 956 gfp_mask);
> 957 if (ret < 0)
> 958 return ret;
> 959
> 960 /* Transfer the folios proposed by the VM into the buffer and take refs
> 961 * on them. The locks will be dropped in netfs_rreq_unlock().
> 962 */
> 963 if (ractl) {
> 964 while ((folio = readahead_folio(ractl))) {
> 965 folio_get(folio);
> 966 if (folio == keep)
> 967 folio_get(folio);
> 968 ret = xa_insert_set_mark(&rreq->buffer,
> 969 folio_index(folio), folio,
> 970 XA_MARK_0, gfp_mask);
> 971 if (ret < 0) {
> 972 if (folio != keep)
> 973 folio_unlock(folio);
> 974 folio_put(folio);
> 975 return ret;
> 976 }
> 977 }
> 978 } else {
> > 979 folio_get(folio);
> 980 ret = xa_insert_set_mark(&rreq->buffer, keep->index, keep,
> 981 XA_MARK_0, gfp_mask);
> 982 if (ret < 0) {
> 983 folio_put(folio);
> 984 return ret;
> 985 }
> 986 }
> 987 return 0;
> 988 }
> 989
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx