From 0d4d70da348b066b02f5aa4b893b13c4e32dc838 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Sat, 10 Oct 2026 01:19:10 -0700 Subject: [PATCH] kbuild: Mark the gzip recipes as recursive 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 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 Acked-by: Lorenzo Stoakes (ARM) Signed-off-by: Kees Cook Tested-by: Paul E. McKenney Link: https://patch.msgid.link/20261010081914.540611-1-kees@kernel.org Signed-off-by: Nathan Chancellor --- Documentation/kbuild/makefiles.rst | 7 +++++-- 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 +- drivers/firmware/efi/libstub/Makefile.zboot | 2 +- usr/Makefile | 2 +- 20 files changed, 26 insertions(+), 23 deletions(-) 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 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: $(obj)/vmlinux.bin.gz diff --git a/drivers/firmware/efi/libstub/Makefile.zboot b/drivers/firmware/efi/libstub/Makefile.zboot index 832deee36e48..52baacf3e9d9 100644 --- a/drivers/firmware/efi/libstub/Makefile.zboot +++ b/drivers/firmware/efi/libstub/Makefile.zboot @@ -24,7 +24,7 @@ zboot-method-$(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/usr/Makefile b/usr/Makefile index e8f42478a0b7..a45236926228 100644 --- a/usr/Makefile +++ b/usr/Makefile @@ -78,7 +78,7 @@ $(obj)/initramfs_data.cpio: $(src)/gen_initramfs.sh $(obj)/gen_init_cpio $(deps_ 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