2022-06-28 01:00:01

by Zhouyi Zhou

[permalink] [raw]
Subject: Possible problem in check-local-export during the kernel build process (RCU torture)

Dear Masahiro:

1. The cause of the problem
When I am doing RCU torture test:

#git clone https://kernel.source.codeaurora.cn/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
#cd linux-rcu
#git checkout remotes/origin/pmladek.2022.06.15a
#./tools/testing/selftests/rcutorture/bin/torture.sh

The kernel building report error something in both Dell PowerEdge R720
and Thinkpad T14 (Amd).

For example:
/mnt/rcu/linux-rcu/tools/testing/selftests/rcutorture/res/2022.06.27-10.42.37-torture#
find . -name Make.out|xargs grep Error
./results-rcutorture-kasan/RUDE01/Make.out:make[2]: ***
[scripts/Makefile.build:257: kernel/trace/power-traces.o] Error 255

2. I trace the problem to check-local-export
I add some echo statement in Makefile.build
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 1f01ac65c0cd..0d48a2d3efff 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -227,13 +227,21 @@ cmd_check_local_export =
$(srctree)/scripts/check-local-export $@

define rule_cc_o_c
$(call cmd_and_fixdep,cc_o_c)
+ echo "after fixdep $$? $<"
$(call cmd,gen_ksymdeps)
+ echo "after gen_ksymdeps $$? $<"
$(call cmd,check_local_export)
+ echo "after check_local_export $$? $<"
$(call cmd,checksrc)
+ echo "after checksrc $$? $<"
$(call cmd,checkdoc)
+ echo "after checkdoc $$? $<"
$(call cmd,gen_objtooldep)
+ echo "after gen_objtooldep $$? $<"
$(call cmd,gen_symversions_c)
+ echo "after gen_symversions $$? $<"
$(call cmd,record_mcount)
+ echo "after record_mcount $$? $<"
endef

Then I rerun the torture.sh

The result show it is check_local_export did not continue in all failed builds.

3. I trace into wait statement in check-local-export
diff --git a/scripts/check-local-export b/scripts/check-local-export
index da745e2743b7..d35477d95bdc 100755
--- a/scripts/check-local-export
+++ b/scripts/check-local-export
@@ -12,7 +12,7 @@ declare -A symbol_types
declare -a export_symbols

exit_code=0
-
+echo "check-local-export L15 ${0} ${1}"
while read value type name
do
# Skip the line if the number of fields is less than 3.
@@ -50,9 +50,10 @@ do
# done < <(${NM} --quiet ${1})
done < <(${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; false; } )

+echo "check-local-export L53 ${0} ${1}"
# Catch error in the process substitution
wait $!
-
+echo "check-local-export L56 ${0} ${1} $! $?"
for name in "${export_symbols[@]}"
do
# nm(3) says "If lowercase, the symbol is usually local"
@@ -61,5 +62,9 @@ do
exit_code=1
fi
done
-
+if [ ${exit_code} -ne 0 ] ; then
+ echo "Zhouyi Zhou"
+ echo ${exit_code}
+fi
+echo "check-local-export L69 $? ${exit_code}"
exit ${exit_code}

Then I rerun the torture.sh

The result show it is wait $! in all failed builds because in all failed cases,
there is L53, but no L56

4. I look into source code of wait command
#wget http://ftp.gnu.org/gnu/bash/bash-5.0.tar.gz
#tar zxf tar zxf bash-5.0.tar.gz
I found that there are QUIT statements in realization of function wait_for

5. My Guess
wait statement in check-local-export may cause bash to quit
I am very interested in this problem, but I am a rookie, I am very
glad to proceed the investigation with your further directions.

Sorry to have brought you so much trouble.


Kind Regard
Thank you very much
Zhouyi


2022-06-28 07:31:32

by Masahiro Yamada

[permalink] [raw]
Subject: Re: Possible problem in check-local-export during the kernel build process (RCU torture)

On Tue, Jun 28, 2022 at 9:55 AM Zhouyi Zhou <[email protected]> wrote:
>
> Dear Masahiro:
>
> 1. The cause of the problem
> When I am doing RCU torture test:
>
> #git clone https://kernel.source.codeaurora.cn/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
> #cd linux-rcu
> #git checkout remotes/origin/pmladek.2022.06.15a
> #./tools/testing/selftests/rcutorture/bin/torture.sh
>
> The kernel building report error something in both Dell PowerEdge R720
> and Thinkpad T14 (Amd).
>
> For example:
> /mnt/rcu/linux-rcu/tools/testing/selftests/rcutorture/res/2022.06.27-10.42.37-torture#
> find . -name Make.out|xargs grep Error
> ./results-rcutorture-kasan/RUDE01/Make.out:make[2]: ***
> [scripts/Makefile.build:257: kernel/trace/power-traces.o] Error 255


check-local-export stopped using the process substitution.
Seet this commit:


commit da4288b95baa1c7c9aa8a476f58b37eb238745b0
Author: Masahiro Yamada <[email protected]>
Date: Wed Jun 8 10:11:00 2022 +0900

scripts/check-local-export: avoid 'wait $!' for process substitution




You are debugging the stale Kbuild code.

If your main interest is RCU torture,
please narrow it down to a standalone script,
not the entire Kbuild.









>
> 2. I trace the problem to check-local-export
> I add some echo statement in Makefile.build
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 1f01ac65c0cd..0d48a2d3efff 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -227,13 +227,21 @@ cmd_check_local_export =
> $(srctree)/scripts/check-local-export $@
>
> define rule_cc_o_c
> $(call cmd_and_fixdep,cc_o_c)
> + echo "after fixdep $$? $<"
> $(call cmd,gen_ksymdeps)
> + echo "after gen_ksymdeps $$? $<"
> $(call cmd,check_local_export)
> + echo "after check_local_export $$? $<"
> $(call cmd,checksrc)
> + echo "after checksrc $$? $<"
> $(call cmd,checkdoc)
> + echo "after checkdoc $$? $<"
> $(call cmd,gen_objtooldep)
> + echo "after gen_objtooldep $$? $<"
> $(call cmd,gen_symversions_c)
> + echo "after gen_symversions $$? $<"
> $(call cmd,record_mcount)
> + echo "after record_mcount $$? $<"
> endef
>
> Then I rerun the torture.sh
>
> The result show it is check_local_export did not continue in all failed builds.
>
> 3. I trace into wait statement in check-local-export
> diff --git a/scripts/check-local-export b/scripts/check-local-export
> index da745e2743b7..d35477d95bdc 100755
> --- a/scripts/check-local-export
> +++ b/scripts/check-local-export
> @@ -12,7 +12,7 @@ declare -A symbol_types
> declare -a export_symbols
>
> exit_code=0
> -
> +echo "check-local-export L15 ${0} ${1}"
> while read value type name
> do
> # Skip the line if the number of fields is less than 3.
> @@ -50,9 +50,10 @@ do
> # done < <(${NM} --quiet ${1})
> done < <(${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; false; } )
>
> +echo "check-local-export L53 ${0} ${1}"
> # Catch error in the process substitution
> wait $!
> -
> +echo "check-local-export L56 ${0} ${1} $! $?"
> for name in "${export_symbols[@]}"
> do
> # nm(3) says "If lowercase, the symbol is usually local"
> @@ -61,5 +62,9 @@ do
> exit_code=1
> fi
> done
> -
> +if [ ${exit_code} -ne 0 ] ; then
> + echo "Zhouyi Zhou"
> + echo ${exit_code}
> +fi
> +echo "check-local-export L69 $? ${exit_code}"
> exit ${exit_code}
>
> Then I rerun the torture.sh
>
> The result show it is wait $! in all failed builds because in all failed cases,
> there is L53, but no L56
>
> 4. I look into source code of wait command
> #wget http://ftp.gnu.org/gnu/bash/bash-5.0.tar.gz
> #tar zxf tar zxf bash-5.0.tar.gz
> I found that there are QUIT statements in realization of function wait_for
>
> 5. My Guess
> wait statement in check-local-export may cause bash to quit
> I am very interested in this problem, but I am a rookie, I am very
> glad to proceed the investigation with your further directions.
>
> Sorry to have brought you so much trouble.
>
>
> Kind Regard
> Thank you very much
> Zhouyi



--
Best Regards
Masahiro Yamada

2022-06-29 00:05:19

by Zhouyi Zhou

[permalink] [raw]
Subject: Re: Possible problem in check-local-export during the kernel build process (RCU torture)

On Tue, Jun 28, 2022 at 3:25 PM Masahiro Yamada <[email protected]> wrote:
>
> On Tue, Jun 28, 2022 at 9:55 AM Zhouyi Zhou <[email protected]> wrote:
> >
> > Dear Masahiro:
> >
> > 1. The cause of the problem
> > When I am doing RCU torture test:
> >
> > #git clone https://kernel.source.codeaurora.cn/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
> > #cd linux-rcu
> > #git checkout remotes/origin/pmladek.2022.06.15a
> > #./tools/testing/selftests/rcutorture/bin/torture.sh
> >
> > The kernel building report error something in both Dell PowerEdge R720
> > and Thinkpad T14 (Amd).
> >
> > For example:
> > /mnt/rcu/linux-rcu/tools/testing/selftests/rcutorture/res/2022.06.27-10.42.37-torture#
> > find . -name Make.out|xargs grep Error
> > ./results-rcutorture-kasan/RUDE01/Make.out:make[2]: ***
> > [scripts/Makefile.build:257: kernel/trace/power-traces.o] Error 255
>
>
> check-local-export stopped using the process substitution.
> Seet this commit:
>
>
> commit da4288b95baa1c7c9aa8a476f58b37eb238745b0
> Author: Masahiro Yamada <[email protected]>
> Date: Wed Jun 8 10:11:00 2022 +0900
>
> scripts/check-local-export: avoid 'wait $!' for process substitution
>
>
>
>
> You are debugging the stale Kbuild code.
Thank Masahiro for your help
I patched da4288b95baa1c7c9aa8a476f58b37eb238745b0 to
pmladek.2022.06.15a branch of linux-rcu, after 13 hours' RCU torture
test,
all the testcases are built successfully!

Tested-by: Zhouyi Zhou <[email protected]>
>
> If your main interest is RCU torture,
> please narrow it down to a standalone script,
> not the entire Kbuild.
OK and Thank you and Paul both for your guidance and encouragement ;-)
>
>
>
>
>
>
>
>
>
> >
> > 2. I trace the problem to check-local-export
> > I add some echo statement in Makefile.build
> > diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> > index 1f01ac65c0cd..0d48a2d3efff 100644
> > --- a/scripts/Makefile.build
> > +++ b/scripts/Makefile.build
> > @@ -227,13 +227,21 @@ cmd_check_local_export =
> > $(srctree)/scripts/check-local-export $@
> >
> > define rule_cc_o_c
> > $(call cmd_and_fixdep,cc_o_c)
> > + echo "after fixdep $$? $<"
> > $(call cmd,gen_ksymdeps)
> > + echo "after gen_ksymdeps $$? $<"
> > $(call cmd,check_local_export)
> > + echo "after check_local_export $$? $<"
> > $(call cmd,checksrc)
> > + echo "after checksrc $$? $<"
> > $(call cmd,checkdoc)
> > + echo "after checkdoc $$? $<"
> > $(call cmd,gen_objtooldep)
> > + echo "after gen_objtooldep $$? $<"
> > $(call cmd,gen_symversions_c)
> > + echo "after gen_symversions $$? $<"
> > $(call cmd,record_mcount)
> > + echo "after record_mcount $$? $<"
> > endef
> >
> > Then I rerun the torture.sh
> >
> > The result show it is check_local_export did not continue in all failed builds.
> >
> > 3. I trace into wait statement in check-local-export
> > diff --git a/scripts/check-local-export b/scripts/check-local-export
> > index da745e2743b7..d35477d95bdc 100755
> > --- a/scripts/check-local-export
> > +++ b/scripts/check-local-export
> > @@ -12,7 +12,7 @@ declare -A symbol_types
> > declare -a export_symbols
> >
> > exit_code=0
> > -
> > +echo "check-local-export L15 ${0} ${1}"
> > while read value type name
> > do
> > # Skip the line if the number of fields is less than 3.
> > @@ -50,9 +50,10 @@ do
> > # done < <(${NM} --quiet ${1})
> > done < <(${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; false; } )
> >
> > +echo "check-local-export L53 ${0} ${1}"
> > # Catch error in the process substitution
> > wait $!
> > -
> > +echo "check-local-export L56 ${0} ${1} $! $?"
> > for name in "${export_symbols[@]}"
> > do
> > # nm(3) says "If lowercase, the symbol is usually local"
> > @@ -61,5 +62,9 @@ do
> > exit_code=1
> > fi
> > done
> > -
> > +if [ ${exit_code} -ne 0 ] ; then
> > + echo "Zhouyi Zhou"
> > + echo ${exit_code}
> > +fi
> > +echo "check-local-export L69 $? ${exit_code}"
> > exit ${exit_code}
> >
> > Then I rerun the torture.sh
> >
> > The result show it is wait $! in all failed builds because in all failed cases,
> > there is L53, but no L56
> >
> > 4. I look into source code of wait command
> > #wget http://ftp.gnu.org/gnu/bash/bash-5.0.tar.gz
> > #tar zxf tar zxf bash-5.0.tar.gz
> > I found that there are QUIT statements in realization of function wait_for
> >
> > 5. My Guess
> > wait statement in check-local-export may cause bash to quit
> > I am very interested in this problem, but I am a rookie, I am very
> > glad to proceed the investigation with your further directions.
> >
> > Sorry to have brought you so much trouble.
> >
> >
> > Kind Regard
> > Thank you very much
> > Zhouyi
>
>
>
> --
> Best Regards
> Masahiro Yamada
Best Regards
Zhouyi