* [PATCH v2 0/2] kbuild: Give jobserver-exec recipes the jobserver
@ 2026-10-10 8:19 Kees Cook
2026-10-10 8:19 ` [PATCH v2 1/2] kbuild: Mark the gzip recipes as recursive Kees Cook
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Kees Cook @ 2026-10-10 8:19 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Kees Cook, Nicolas Schier, Lorenzo Stoakes, Manuel Ebner,
Ard Biesheuvel, Paul E . McKenney, Nicolas Schier, Sami Tolvanen,
linux-kbuild, llvm, linux-kernel, linux-hardening
Hi!
Paul reported a build failure on CentOS Stream 9 with linux-next[1]: the
kernel builds, but scripts/jobserver-exec prints
WARNING: Unable to reopen jobserver read-side pipe: FileNotFoundError(2, 'No such file or directory')
and rcutorture's build check counts the "Error" in that line. CentOS's
make 4.3 carries a backport of the fix for GNU Make bug 58232, so
sub-makes, like the top-level make, give the jobserver pipe only to
recipes marked recursive, while MAKEFLAGS still names it. The new pigz
steps (1/2), for the kernel image, the built-in initramfs, and the other
gzip rules, and the older Clang LTO initcall ordering step (2/2) run
jobserver-exec from recipes without "+", so pigz gets one thread and the
initcall script caps its children at the CPU count instead of the free
job slots. Mark these recipes recursive, as was done for rustc.
Thanks!
-Kees
v2:
- 1/2: also mark the gzip rules that choose gzip through a variable,
including the built-in initramfs in usr/Makefile, which rcutorture's
kvm.sh builds and v1 missed (Paul)
- 1/2: update the gzip entry in Documentation/kbuild/makefiles.rst
(Nicolas)
- 2/2: cite Masahiro's earlier version of this change and say when the
script gets more than one archive (Nicolas)
- v1..v2 diff: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/diff/?id=dev/next-20261001/pigz-recursive/v2&id2=dev/next-20261001/pigz-recursive/v1
v1: https://lore.kernel.org/all/20261009062722.i.253-kees@kernel.org/
[1] https://lore.kernel.org/all/0ddb5e5e-f801-444c-aa98-0cfe814a3026@paulmck-laptop/
Kees Cook (2):
kbuild: Mark the gzip recipes as recursive
kbuild: Mark the initcall ordering recipe as recursive
arch/alpha/boot/Makefile | 4 ++--
arch/arc/boot/Makefile | 2 +-
arch/arm/boot/compressed/Makefile | 2 +-
arch/arm64/boot/Makefile | 2 +-
arch/csky/boot/Makefile | 2 +-
arch/microblaze/boot/Makefile | 2 +-
arch/mips/boot/Makefile | 2 +-
arch/mips/boot/compressed/Makefile | 2 +-
arch/nios2/boot/Makefile | 2 +-
arch/parisc/boot/compressed/Makefile | 2 +-
arch/riscv/boot/Makefile | 2 +-
arch/s390/boot/Makefile | 2 +-
arch/sh/boot/Makefile | 2 +-
arch/sh/boot/compressed/Makefile | 2 +-
arch/sparc/boot/Makefile | 4 ++--
arch/x86/boot/compressed/Makefile | 2 +-
arch/xtensa/boot/Makefile | 2 +-
usr/Makefile | 2 +-
drivers/firmware/efi/libstub/Makefile.zboot | 2 +-
scripts/Makefile.vmlinux_o | 2 +-
Documentation/kbuild/makefiles.rst | 7 +++++--
21 files changed, 27 insertions(+), 24 deletions(-)
--
2.55.0
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v2 1/2] kbuild: Mark the gzip recipes as recursive
2026-10-10 8:19 [PATCH v2 0/2] kbuild: Give jobserver-exec recipes the jobserver Kees Cook
@ 2026-10-10 8:19 ` Kees Cook
2026-10-10 8:19 ` [PATCH v2 2/2] kbuild: Mark the initcall ordering recipe " Kees Cook
2026-10-10 13:48 ` [PATCH v2 0/2] kbuild: Give jobserver-exec recipes the jobserver Nathan Chancellor
2 siblings, 0 replies; 4+ messages in thread
From: Kees Cook @ 2026-10-10 8:19 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Kees Cook, Nicolas Schier, Lorenzo Stoakes, Manuel Ebner,
linux-kbuild, Ard Biesheuvel, Paul E. McKenney, Nicolas Schier,
linux-kernel, linux-hardening
Since commit 48ebe1cbbeb51 ("kbuild: compress the kernel with pigz if
available"), cmd_gzip runs pigz through scripts/jobserver-exec, which
takes the job slots make has free. GNU Make passes the jobserver pipe
only to recipes it treats as recursive, but leaves --jobserver-auth in
MAKEFLAGS for all of them. The make 4.3 in CentOS Stream 9 also hides
the pipe in sub-makes (a backport of the fix for GNU Make bug 58232), so
jobserver-exec cannot open it, runs pigz on one thread, and prints:
WARNING: Unable to reopen jobserver read-side pipe: FileNotFoundError(2, 'No such file or directory')
Mark every recipe that can run cmd_gzip as recursive with "+", as
commit ecab4115c44cc ("kbuild: mark `rustc` (and others) invocations as
recursive") did for rustc. Besides the $(call if_changed,gzip) rules,
this covers those that choose gzip through a variable: the built-in
initramfs in usr/Makefile (which rcutorture's kvm.sh builds), the EFI
zboot image, and the arm, csky, and mips compressed images. As with
rustc, "make -n" now runs these recipes, including those that choose
through a variable when they select another compressor. Also update the
gzip entry in Documentation/kbuild/makefiles.rst, as suggested in
review.
Tested with GNU Make 4.3 plus CentOS Stream 9's make-4.3-cloexec.patch,
GCC 16.2.0, and -j64, on ARCH=x86_64, arm64, and arm defconfig, and
ARCH=x86_64 defconfig with a built-in initramfs: none of them prints the
warning, and pigz gets the free job slots (-p 54, 64, and 50 for the
kernel image). Without this change, the x86_64 builds print it for the
kernel image and for the initramfs.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Closes: https://lore.kernel.org/all/0ddb5e5e-f801-444c-aa98-0cfe814a3026@paulmck-laptop/
Fixes: 48ebe1cbbeb51 ("kbuild: compress the kernel with pigz if available")
Assisted-by: LLM
Reviewed-by: Nicolas Schier <n.schier@fritz.com>
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Signed-off-by: Kees Cook <kees@kernel.org>
---
arch/alpha/boot/Makefile | 4 ++--
arch/arc/boot/Makefile | 2 +-
arch/arm/boot/compressed/Makefile | 2 +-
arch/arm64/boot/Makefile | 2 +-
arch/csky/boot/Makefile | 2 +-
arch/microblaze/boot/Makefile | 2 +-
arch/mips/boot/Makefile | 2 +-
arch/mips/boot/compressed/Makefile | 2 +-
arch/nios2/boot/Makefile | 2 +-
arch/parisc/boot/compressed/Makefile | 2 +-
arch/riscv/boot/Makefile | 2 +-
arch/s390/boot/Makefile | 2 +-
arch/sh/boot/Makefile | 2 +-
arch/sh/boot/compressed/Makefile | 2 +-
arch/sparc/boot/Makefile | 4 ++--
arch/x86/boot/compressed/Makefile | 2 +-
arch/xtensa/boot/Makefile | 2 +-
usr/Makefile | 2 +-
drivers/firmware/efi/libstub/Makefile.zboot | 2 +-
Documentation/kbuild/makefiles.rst | 7 +++++--
20 files changed, 26 insertions(+), 23 deletions(-)
diff --git a/arch/alpha/boot/Makefile b/arch/alpha/boot/Makefile
index d8dba85e606c..b050753e9015 100644
--- a/arch/alpha/boot/Makefile
+++ b/arch/alpha/boot/Makefile
@@ -40,7 +40,7 @@ endif
# Compressed kernel image
$(obj)/vmlinux.gz: $(obj)/vmlinux FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
@echo ' Kernel $@ is ready'
$(obj)/main.o: $(obj)/ksize.h
@@ -85,7 +85,7 @@ $(obj)/vmlinux.nh: vmlinux $(OBJSTRIP) FORCE
$(call if_changed,objstrip)
$(obj)/vmlinux.nh.gz: $(obj)/vmlinux.nh FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
$(obj)/tools/lxboot: $(obj)/bootloader $(OBJSTRIP) FORCE
$(call if_changed,objstrip)
diff --git a/arch/arc/boot/Makefile b/arch/arc/boot/Makefile
index 5a8550124b73..8a44c3e7ff3e 100644
--- a/arch/arc/boot/Makefile
+++ b/arch/arc/boot/Makefile
@@ -23,7 +23,7 @@ $(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
$(obj)/vmlinux.bin.lzma: $(obj)/vmlinux.bin FORCE
$(call if_changed,lzma)
diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index e3f550d62857..5f0a1a2e915a 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -153,7 +153,7 @@ $(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/$(HEAD) $(obj)/piggy.o \
@$(check_for_bad_syms)
$(obj)/piggy_data: $(obj)/../Image FORCE
- $(call if_changed,$(compress-y))
+ +$(call if_changed,$(compress-y))
$(obj)/piggy.o: $(obj)/piggy_data
diff --git a/arch/arm64/boot/Makefile b/arch/arm64/boot/Makefile
index b5a08333bc57..d42d07667822 100644
--- a/arch/arm64/boot/Makefile
+++ b/arch/arm64/boot/Makefile
@@ -26,7 +26,7 @@ $(obj)/Image.bz2: $(obj)/Image FORCE
$(call if_changed,bzip2)
$(obj)/Image.gz: $(obj)/Image FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
$(obj)/Image.lz4: $(obj)/Image FORCE
$(call if_changed,lz4)
diff --git a/arch/csky/boot/Makefile b/arch/csky/boot/Makefile
index c3cfde28f8e6..5d88dc31877b 100644
--- a/arch/csky/boot/Makefile
+++ b/arch/csky/boot/Makefile
@@ -12,7 +12,7 @@ compress-$(CONFIG_KERNEL_XZ) = xzkern
compress-$(CONFIG_KERNEL_LZ4) = lz4
$(obj)/zImage: $(obj)/Image FORCE
- $(call if_changed,$(compress-y))
+ +$(call if_changed,$(compress-y))
@echo ' Kernel: $@ is ready'
UIMAGE_ARCH = sandbox
diff --git a/arch/microblaze/boot/Makefile b/arch/microblaze/boot/Makefile
index 2b42c370d574..e3df3a64808a 100644
--- a/arch/microblaze/boot/Makefile
+++ b/arch/microblaze/boot/Makefile
@@ -14,7 +14,7 @@ $(obj)/linux.bin.ub: $(obj)/linux.bin FORCE
$(call if_changed,uimage)
$(obj)/linux.bin.gz: $(obj)/linux.bin FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
quiet_cmd_strip = STRIP $< $@$2
cmd_strip = $(STRIP) -K microblaze_start -K _end -K __log_buf \
diff --git a/arch/mips/boot/Makefile b/arch/mips/boot/Makefile
index 8473c4671702..996bf41b78de 100644
--- a/arch/mips/boot/Makefile
+++ b/arch/mips/boot/Makefile
@@ -63,7 +63,7 @@ $(obj)/vmlinux.bin.bz2: $(obj)/vmlinux.bin FORCE
$(call if_changed,bzip2)
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
$(obj)/vmlinux.bin.lzma: $(obj)/vmlinux.bin FORCE
$(call if_changed,lzma)
diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
index e0b8ec9a9516..2684540758a8 100644
--- a/arch/mips/boot/compressed/Makefile
+++ b/arch/mips/boot/compressed/Makefile
@@ -69,7 +69,7 @@ tool_$(CONFIG_KERNEL_ZSTD) = zstd22_with_size
targets += vmlinux.bin.z
$(obj)/vmlinux.bin.z: $(obj)/vmlinux.bin FORCE
- $(call if_changed,$(tool_y))
+ +$(call if_changed,$(tool_y))
targets += piggy.o dummy.o
diff --git a/arch/nios2/boot/Makefile b/arch/nios2/boot/Makefile
index 29c11a06b750..1381e6e428a8 100644
--- a/arch/nios2/boot/Makefile
+++ b/arch/nios2/boot/Makefile
@@ -18,7 +18,7 @@ $(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
$(obj)/vmlinux.gz: $(obj)/vmlinux.bin FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
$(obj)/vmImage: $(obj)/vmlinux.gz FORCE
$(call if_changed,uimage)
diff --git a/arch/parisc/boot/compressed/Makefile b/arch/parisc/boot/compressed/Makefile
index 14eefb5ed5d1..a7fc7d424c00 100644
--- a/arch/parisc/boot/compressed/Makefile
+++ b/arch/parisc/boot/compressed/Makefile
@@ -55,7 +55,7 @@ suffix-$(CONFIG_KERNEL_LZO) := lzo
suffix-$(CONFIG_KERNEL_XZ) := xz
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
$(obj)/vmlinux.bin.bz2: $(obj)/vmlinux.bin FORCE
$(call if_changed,bzip2_with_size)
$(obj)/vmlinux.bin.lz4: $(obj)/vmlinux.bin FORCE
diff --git a/arch/riscv/boot/Makefile b/arch/riscv/boot/Makefile
index 4a2d75b7e42d..b80a077a8e8f 100644
--- a/arch/riscv/boot/Makefile
+++ b/arch/riscv/boot/Makefile
@@ -23,7 +23,7 @@ $(obj)/Image: vmlinux FORCE
$(call if_changed,objcopy)
$(obj)/Image.gz: $(obj)/Image FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
$(obj)/loader.o: $(src)/loader.S $(obj)/Image
diff --git a/arch/s390/boot/Makefile b/arch/s390/boot/Makefile
index 10b75e053a6f..e8e43ae80dd5 100644
--- a/arch/s390/boot/Makefile
+++ b/arch/s390/boot/Makefile
@@ -117,7 +117,7 @@ suffix-$(CONFIG_KERNEL_XZ) := .xz
suffix-$(CONFIG_KERNEL_ZSTD) := .zst
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
$(obj)/vmlinux.bin.bz2: $(obj)/vmlinux.bin FORCE
$(call if_changed,bzip2_with_size)
$(obj)/vmlinux.bin.lz4: $(obj)/vmlinux.bin FORCE
diff --git a/arch/sh/boot/Makefile b/arch/sh/boot/Makefile
index 1f5d2df3c7e0..cf63e319b786 100644
--- a/arch/sh/boot/Makefile
+++ b/arch/sh/boot/Makefile
@@ -66,7 +66,7 @@ $(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
$(obj)/vmlinux.bin.bz2: $(obj)/vmlinux.bin FORCE
$(call if_changed,bzip2)
diff --git a/arch/sh/boot/compressed/Makefile b/arch/sh/boot/compressed/Makefile
index 58df491778b2..b85aa5f0d616 100644
--- a/arch/sh/boot/compressed/Makefile
+++ b/arch/sh/boot/compressed/Makefile
@@ -39,7 +39,7 @@ $(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
$(obj)/vmlinux.bin.bz2: $(obj)/vmlinux.bin FORCE
$(call if_changed,bzip2_with_size)
$(obj)/vmlinux.bin.lzma: $(obj)/vmlinux.bin FORCE
diff --git a/arch/sparc/boot/Makefile b/arch/sparc/boot/Makefile
index 339c42d35089..b53cf596611e 100644
--- a/arch/sparc/boot/Makefile
+++ b/arch/sparc/boot/Makefile
@@ -23,7 +23,7 @@ ifeq ($(CONFIG_SPARC64),y)
# Actual linking
$(obj)/zImage: $(obj)/image FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
@$(kecho) 'Kernel: $@ is ready' '(#'$(or $(KBUILD_BUILD_VERSION),`cat .version`)')'
$(obj)/vmlinux.aout: vmlinux FORCE
@@ -45,7 +45,7 @@ $(obj)/image.bin: $(obj)/image FORCE
$(call if_changed,objcopy)
$(obj)/image.gz: $(obj)/image.bin FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
UIMAGE_LOADADDR = $(CONFIG_UBOOT_LOAD_ADDR)
UIMAGE_ENTRYADDR = $(CONFIG_UBOOT_ENTRY_ADDR)
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 6ec5e031db1d..680ad803cba7 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -133,7 +133,7 @@ vmlinux.bin.all-y := $(obj)/vmlinux.bin
vmlinux.bin.all-$(CONFIG_X86_NEED_RELOCS) += $(obj)/vmlinux.relocs
$(obj)/vmlinux.bin.gz: $(vmlinux.bin.all-y) FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
$(obj)/vmlinux.bin.bz2: $(vmlinux.bin.all-y) FORCE
$(call if_changed,bzip2_with_size)
$(obj)/vmlinux.bin.lzma: $(vmlinux.bin.all-y) FORCE
diff --git a/arch/xtensa/boot/Makefile b/arch/xtensa/boot/Makefile
index d8b0fadf429a..934f9015b15f 100644
--- a/arch/xtensa/boot/Makefile
+++ b/arch/xtensa/boot/Makefile
@@ -36,7 +36,7 @@ $(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
boot-elf: $(obj)/vmlinux.bin
boot-redboot: $(obj)/vmlinux.bin.gz
diff --git a/usr/Makefile b/usr/Makefile
index 5b97ee66c00a..975c68e5b6b6 100644
--- a/usr/Makefile
+++ b/usr/Makefile
@@ -76,7 +76,7 @@ $(obj)/initramfs_data.cpio: $(srctree)/scripts/gen_initramfs.sh scripts/gen_init
endif
$(obj)/initramfs_inc_data: $(cpio-data) FORCE
- $(call if_changed,$(compress-y))
+ +$(call if_changed,$(compress-y))
targets += initramfs_data.cpio initramfs_inc_data
diff --git a/drivers/firmware/efi/libstub/Makefile.zboot b/drivers/firmware/efi/libstub/Makefile.zboot
index 832deee36e48..52baacf3e9d9 100644
--- a/drivers/firmware/efi/libstub/Makefile.zboot
+++ b/drivers/firmware/efi/libstub/Makefile.zboot
@@ -24,7 +24,7 @@ zboot-method-$(CONFIG_KERNEL_ZSTD) := zstd22_with_size
zboot-size-len-$(CONFIG_KERNEL_ZSTD) := 4
$(obj)/vmlinuz: $(obj)/vmlinux.bin FORCE
- $(call if_changed,$(zboot-method-y))
+ +$(call if_changed,$(zboot-method-y))
# avoid eager evaluation to prevent references to non-existent build artifacts
OBJCOPYFLAGS_vmlinuz.o = -I binary -O $(EFI_ZBOOT_BFD_TARGET) $(EFI_ZBOOT_OBJCOPY_FLAGS) \
diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst
index 7521cae7d56f..535d30eef59a 100644
--- a/Documentation/kbuild/makefiles.rst
+++ b/Documentation/kbuild/makefiles.rst
@@ -1452,13 +1452,16 @@ objcopy
OBJCOPYFLAGS_$@ may be used to set additional options.
gzip
- Compress target. Use maximum compression to compress target.
+ Compress target. Use maximum compression to compress target. Prefix the
+ recipe line with '+' so that GNU Make passes it the jobserver, which
+ scripts/jobserver-exec needs to run pigz (if available) on the free job
+ slots.
Example::
#arch/x86/boot/compressed/Makefile
$(obj)/vmlinux.bin.gz: $(vmlinux.bin.all-y) FORCE
- $(call if_changed,gzip)
+ +$(call if_changed,gzip)
dtc
Create flattened device tree blob object suitable for linking
--
2.55.0
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v2 2/2] kbuild: Mark the initcall ordering recipe as recursive
2026-10-10 8:19 [PATCH v2 0/2] kbuild: Give jobserver-exec recipes the jobserver Kees Cook
2026-10-10 8:19 ` [PATCH v2 1/2] kbuild: Mark the gzip recipes as recursive Kees Cook
@ 2026-10-10 8:19 ` Kees Cook
2026-10-10 13:48 ` [PATCH v2 0/2] kbuild: Give jobserver-exec recipes the jobserver Nathan Chancellor
2 siblings, 0 replies; 4+ messages in thread
From: Kees Cook @ 2026-10-10 8:19 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Kees Cook, Nicolas Schier, Sami Tolvanen, linux-kbuild, llvm,
Nicolas Schier, linux-kernel, linux-hardening
generate_initcall_order.pl, which orders initcalls for Clang LTO, forks
a child per input file, up to the job count scripts/jobserver-exec
passes it in PARALLELISM. It used to run from link-vmlinux.sh, which
the top-level Makefile invokes as a recursive recipe, but
commit 5d45950dfbb15 ("kbuild: move vmlinux.o link to
scripts/Makefile.vmlinux_o") moved it into a recipe without "+".
GNU Make passes the jobserver pipe only to recipes it treats as
recursive, and the make 4.3 in CentOS Stream 9 also hides it in
sub-makes (a backport of the fix for GNU Make bug 58232), so
jobserver-exec cannot open it and prints:
WARNING: Unable to reopen jobserver read-side pipe: FileNotFoundError(2, 'No such file or directory')
PARALLELISM is then left unset, and the script caps its children at the
number of online CPUs instead of the free job slots.
Mark the recipe as recursive again (this makes "make -n" runs the script
again too, as it did from link-vmlinux.sh). Masahiro posted the same
change and withdrew it because the script was given only vmlinux.a, and
so never ran more than one child [1]. But on arm64, LoongArch, and RISC-V
with CONFIG_EFI_STUB, KBUILD_VMLINUX_LIBS also gives it the EFI stub's
lib.a. Either way, the warning is silenced.
Tested ARCH=x86_64 defconfig with CONFIG_LTO_CLANG_THIN=y, LLVM=1
(Clang 24.0.0git), and GNU Make 4.3 plus CentOS Stream 9's
make-4.3-cloexec.patch.
Fixes: 5d45950dfbb15 ("kbuild: move vmlinux.o link to scripts/Makefile.vmlinux_o")
Link: https://lore.kernel.org/all/CAK7LNARCM=rUm8mA8GRQ7ufeyfneGf4OEvHmESKt=zuxs2KrHw@mail.gmail.com/ [1]
Assisted-by: LLM
Reviewed-by: Nicolas Schier <n.schier@fritz.com>
Signed-off-by: Kees Cook <kees@kernel.org>
---
scripts/Makefile.vmlinux_o | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/scripts/Makefile.vmlinux_o b/scripts/Makefile.vmlinux_o
index 24a3a4fd271c..0b37bd5dc3a4 100644
--- a/scripts/Makefile.vmlinux_o
+++ b/scripts/Makefile.vmlinux_o
@@ -19,7 +19,7 @@ quiet_cmd_gen_initcalls_lds = GEN $@
.tmp_initcalls.lds: $(srctree)/scripts/generate_initcall_order.pl \
vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE
- $(call if_changed,gen_initcalls_lds)
+ +$(call if_changed,gen_initcalls_lds)
targets := .tmp_initcalls.lds
--
2.55.0
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2 0/2] kbuild: Give jobserver-exec recipes the jobserver
2026-10-10 8:19 [PATCH v2 0/2] kbuild: Give jobserver-exec recipes the jobserver Kees Cook
2026-10-10 8:19 ` [PATCH v2 1/2] kbuild: Mark the gzip recipes as recursive Kees Cook
2026-10-10 8:19 ` [PATCH v2 2/2] kbuild: Mark the initcall ordering recipe " Kees Cook
@ 2026-10-10 13:48 ` Nathan Chancellor
2 siblings, 0 replies; 4+ messages in thread
From: Nathan Chancellor @ 2026-10-10 13:48 UTC (permalink / raw)
To: Kees Cook
Cc: Nicolas Schier, Lorenzo Stoakes, Manuel Ebner, Ard Biesheuvel,
Paul E . McKenney, Nicolas Schier, Sami Tolvanen, linux-kbuild,
llvm, linux-kernel, linux-hardening
On Sat, Oct 10, 2026 at 01:19:09AM -0700, Kees Cook wrote:
> Hi!
>
> Paul reported a build failure on CentOS Stream 9 with linux-next[1]: the
> kernel builds, but scripts/jobserver-exec prints
>
> WARNING: Unable to reopen jobserver read-side pipe: FileNotFoundError(2, 'No such file or directory')
>
> and rcutorture's build check counts the "Error" in that line. CentOS's
> make 4.3 carries a backport of the fix for GNU Make bug 58232, so
> sub-makes, like the top-level make, give the jobserver pipe only to
> recipes marked recursive, while MAKEFLAGS still names it. The new pigz
> steps (1/2), for the kernel image, the built-in initramfs, and the other
> gzip rules, and the older Clang LTO initcall ordering step (2/2) run
> jobserver-exec from recipes without "+", so pigz gets one thread and the
> initcall script caps its children at the CPU count instead of the free
> job slots. Mark these recipes recursive, as was done for rustc.
>
> Thanks!
>
> -Kees
>
> v2:
> - 1/2: also mark the gzip rules that choose gzip through a variable,
> including the built-in initramfs in usr/Makefile, which rcutorture's
> kvm.sh builds and v1 missed (Paul)
> - 1/2: update the gzip entry in Documentation/kbuild/makefiles.rst
> (Nicolas)
> - 2/2: cite Masahiro's earlier version of this change and say when the
> script gets more than one archive (Nicolas)
> - v1..v2 diff: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/diff/?id=dev/next-20261001/pigz-recursive/v2&id2=dev/next-20261001/pigz-recursive/v1
> v1: https://lore.kernel.org/all/20261009062722.i.253-kees@kernel.org/
>
> [1] https://lore.kernel.org/all/0ddb5e5e-f801-444c-aa98-0cfe814a3026@paulmck-laptop/
>
> Kees Cook (2):
> kbuild: Mark the gzip recipes as recursive
> kbuild: Mark the initcall ordering recipe as recursive
I've kicked these into -next, I will formally apply them to
kbuild-next-speedups once Paul can confirm that it resolves his
regression. Thanks a lot for the assist here!
--
Cheers,
Nathan
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-10-10 13:48 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2026-10-10 8:19 [PATCH v2 0/2] kbuild: Give jobserver-exec recipes the jobserver Kees Cook
2026-10-10 8:19 ` [PATCH v2 1/2] kbuild: Mark the gzip recipes as recursive Kees Cook
2026-10-10 8:19 ` [PATCH v2 2/2] kbuild: Mark the initcall ordering recipe " Kees Cook
2026-10-10 13:48 ` [PATCH v2 0/2] kbuild: Give jobserver-exec recipes the jobserver Nathan Chancellor
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