[PATCH 0/5] treewide: remove unreachable memblock_reserve() return value checks in early boot

[PATCH 0/5] treewide: remove unreachable memblock_reserve() return value checks in early boot

[Sang-Heon Jeon]

memblock_reserve() can only return an error after memblock_allow_resize()
has been called. Before that it either succeeds or panics, never returning
an error.

Before memblock_allow_resize() is called, the return value checks of
memblock_reserve() are unreachable and can be removed.

All the call sites are in different trees, so I split the change into one
patch per arch/subsystem. The patches are independent and can be applied
separately.

Sang-Heon Jeon (5):
  x86/setup: remove unreachable memblock_reserve() return value check
  sh: remove unreachable memblock_reserve() return value check
  powerpc/fadump: remove unreachable memblock_reserve() return value
    checks
  xtensa: remove unreachable memblock_reserve() return value checks
  Revert "tpm: do not ignore memblock_reserve return value"

 arch/powerpc/kernel/fadump.c   | 14 +++-----------
 arch/sh/kernel/machine_kexec.c |  7 +------
 arch/x86/kernel/setup.c        |  7 ++-----
 arch/xtensa/kernel/setup.c     | 13 +++++++------
 drivers/firmware/efi/tpm.c     |  7 +------
 5 files changed, 14 insertions(+), 34 deletions(-)

-- 
2.43.0

[PATCH 1/5] x86/setup: remove unreachable memblock_reserve() return value check

[Sang-Heon Jeon]

trim_snb_memory() runs from early_reserve_memory() in setup_arch(), before
e820__memblock_setup() calls memblock_allow_resize(). At that point
memblock_reserve() either succeeds or panics, never returning an error.

Therefore the return value check is unreachable, so remove it and the
related logic.

No functional change.

Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
---
 arch/x86/kernel/setup.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 46882ce79c3a..f9395bc632ca 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -742,11 +742,8 @@ static void __init trim_snb_memory(void)
 	 * setup_arch(), so there is no need to reserve it here.
 	 */
 
-	for (i = 0; i < ARRAY_SIZE(bad_pages); i++) {
-		if (memblock_reserve(bad_pages[i], PAGE_SIZE))
-			printk(KERN_WARNING "failed to reserve 0x%08lx\n",
-			       bad_pages[i]);
-	}
+	for (i = 0; i < ARRAY_SIZE(bad_pages); i++)
+		memblock_reserve(bad_pages[i], PAGE_SIZE);
 }
 
 static void __init trim_bios_range(void)
-- 
2.43.0

[PATCH 2/5] sh: remove unreachable memblock_reserve() return value check

[Sang-Heon Jeon]

reserve_crashkernel() runs from early_reserve_mem() in paging_init(),
before the same function calls memblock_allow_resize(). At that point
memblock_reserve() either succeeds or panics, never returning an error.

Therefore the return value check is unreachable, so remove it and the
related logic.

No functional change.

Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
---
 arch/sh/kernel/machine_kexec.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/arch/sh/kernel/machine_kexec.c b/arch/sh/kernel/machine_kexec.c
index 37073ca1e0ad..ba9c412f14d9 100644
--- a/arch/sh/kernel/machine_kexec.c
+++ b/arch/sh/kernel/machine_kexec.c
@@ -165,12 +165,7 @@ void __init reserve_crashkernel(void)
 			goto disable;
 		}
 	} else {
-		ret = memblock_reserve(crashk_res.start, crash_size);
-		if (unlikely(ret < 0)) {
-			pr_err("crashkernel reservation failed - "
-			       "memory is in use\n");
-			goto disable;
-		}
+		memblock_reserve(crashk_res.start, crash_size);
 	}
 
 	crashk_res.end = crashk_res.start + crash_size - 1;
-- 
2.43.0

[PATCH 3/5] powerpc/fadump: remove unreachable memblock_reserve() return value checks

[Sang-Heon Jeon]

fadump_append_bootargs() and fadump_reserve_mem() both run from
early_init_devtree(), before it calls memblock_allow_resize(). At that
point memblock_reserve() either succeeds or panics, never returning an
error.

Therefore the return value checks are unreachable, so remove them and the
related logic.

No functional change.

Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
---
 arch/powerpc/kernel/fadump.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index a313b1653124..88ca6156b81a 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -154,13 +154,8 @@ void __init fadump_append_bootargs(void)
 	if (!fw_dump.dump_active || !fw_dump.param_area_supported || !fw_dump.param_area)
 		return;
 
-	if (fw_dump.param_area < fw_dump.boot_mem_top) {
-		if (memblock_reserve(fw_dump.param_area, COMMAND_LINE_SIZE)) {
-			pr_warn("WARNING: Can't use additional parameters area!\n");
-			fw_dump.param_area = 0;
-			return;
-		}
-	}
+	if (fw_dump.param_area < fw_dump.boot_mem_top)
+		memblock_reserve(fw_dump.param_area, COMMAND_LINE_SIZE);
 
 	append_args = (char *)fw_dump.param_area;
 	len = strlen(boot_command_line);
@@ -632,10 +627,7 @@ int __init fadump_reserve_mem(void)
 		    (fw_dump.ops->fadump_setup_metadata(&fw_dump) < 0))
 			goto error_out;
 
-		if (memblock_reserve(base, size)) {
-			pr_err("Failed to reserve memory!\n");
-			goto error_out;
-		}
+		memblock_reserve(base, size);
 
 		pr_info("Reserved %lldMB of memory at %#016llx (System RAM: %lldMB)\n",
 			(size >> 20), base, (memblock_phys_mem_size() >> 20));
-- 
2.43.0

Re: [PATCH 3/5] powerpc/fadump: remove unreachable memblock_reserve() return value checks

[Mukesh Kumar Chaurasiya]

On Wed, Jun 17, 2026 at 03:29:54AM +0900, Sang-Heon Jeon wrote:
> fadump_append_bootargs() and fadump_reserve_mem() both run from
> early_init_devtree(), before it calls memblock_allow_resize(). At that
> point memblock_reserve() either succeeds or panics, never returning an
> error.
> 
> Therefore the return value checks are unreachable, so remove them and the
> related logic.
> 
> No functional change.
> 
> Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
> ---
>  arch/powerpc/kernel/fadump.c | 14 +++-----------
>  1 file changed, 3 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
> index a313b1653124..88ca6156b81a 100644
> --- a/arch/powerpc/kernel/fadump.c
> +++ b/arch/powerpc/kernel/fadump.c
> @@ -154,13 +154,8 @@ void __init fadump_append_bootargs(void)
>  	if (!fw_dump.dump_active || !fw_dump.param_area_supported || !fw_dump.param_area)
>  		return;
>  
> -	if (fw_dump.param_area < fw_dump.boot_mem_top) {
> -		if (memblock_reserve(fw_dump.param_area, COMMAND_LINE_SIZE)) {
> -			pr_warn("WARNING: Can't use additional parameters area!\n");
> -			fw_dump.param_area = 0;
> -			return;
> -		}
> -	}
> +	if (fw_dump.param_area < fw_dump.boot_mem_top)
> +		memblock_reserve(fw_dump.param_area, COMMAND_LINE_SIZE);
>  
>  	append_args = (char *)fw_dump.param_area;
>  	len = strlen(boot_command_line);
> @@ -632,10 +627,7 @@ int __init fadump_reserve_mem(void)
>  		    (fw_dump.ops->fadump_setup_metadata(&fw_dump) < 0))
>  			goto error_out;
>  
> -		if (memblock_reserve(base, size)) {
> -			pr_err("Failed to reserve memory!\n");
> -			goto error_out;
> -		}
> +		memblock_reserve(base, size);
>  
>  		pr_info("Reserved %lldMB of memory at %#016llx (System RAM: %lldMB)\n",
>  			(size >> 20), base, (memblock_phys_mem_size() >> 20));
> -- 
> 2.43.0
> 
Yeah, that's a dead code.

Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>

[PATCH 4/5] xtensa: remove unreachable memblock_reserve() return value checks

[Sang-Heon Jeon]

mem_reserve() wraps memblock_reserve(), and its callers check the return
value. xtensa never calls memblock_allow_resize(), so memblock_reserve()
either succeeds or panics, never returning an error.

Therefore the return value checks are unreachable, so remove them and make
mem_reserve() return void.

No functional change.

Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
---
 arch/xtensa/kernel/setup.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/xtensa/kernel/setup.c b/arch/xtensa/kernel/setup.c
index f72e280363be..c7367b81cc36 100644
--- a/arch/xtensa/kernel/setup.c
+++ b/arch/xtensa/kernel/setup.c
@@ -268,10 +268,10 @@ void __init init_arch(bp_tag_t *bp_start)
  * Initialize system. Setup memory and reserve regions.
  */
 
-static inline int __init_memblock mem_reserve(unsigned long start,
-					      unsigned long end)
+static inline void __init_memblock mem_reserve(unsigned long start,
+					       unsigned long end)
 {
-	return memblock_reserve(start, end - start);
+	memblock_reserve(start, end - start);
 }
 
 void __init setup_arch(char **cmdline_p)
@@ -290,11 +290,12 @@ void __init setup_arch(char **cmdline_p)
 	/* Reserve some memory regions */
 
 #ifdef CONFIG_BLK_DEV_INITRD
-	if (initrd_start < initrd_end &&
-	    !mem_reserve(__pa(initrd_start), __pa(initrd_end)))
+	if (initrd_start < initrd_end) {
+		mem_reserve(__pa(initrd_start), __pa(initrd_end));
 		initrd_below_start_ok = 1;
-	else
+	} else {
 		initrd_start = 0;
+	}
 #endif
 
 	mem_reserve(__pa(_stext), __pa(_end));
-- 
2.43.0

[PATCH 5/5] Revert "tpm: do not ignore memblock_reserve return value"

[Sang-Heon Jeon]

This reverts commit c33c28f9f6e017702374e1ab907dfa5a63db5301.

efi_tpm_eventlog_init() runs from efi_config_parse_tables() during early
EFI initialization, before memblock_allow_resize(). At that point
memblock_reserve() either succeeds or panics, never returning an error.

Therefore the return value check is unreachable, so restore the original
unconditional memblock_reserve().

No functional change.

Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
---
 drivers/firmware/efi/tpm.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c
index cdd431027065..288bcf7a5b99 100644
--- a/drivers/firmware/efi/tpm.c
+++ b/drivers/firmware/efi/tpm.c
@@ -61,12 +61,7 @@ int __init efi_tpm_eventlog_init(void)
 	}
 
 	tbl_size = sizeof(*log_tbl) + log_tbl->size;
-	if (memblock_reserve(efi.tpm_log, tbl_size)) {
-		pr_err("TPM Event Log memblock reserve fails (0x%lx, 0x%x)\n",
-		       efi.tpm_log, tbl_size);
-		ret = -ENOMEM;
-		goto out;
-	}
+	memblock_reserve(efi.tpm_log, tbl_size);
 
 	if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR) {
 		pr_info("TPM Final Events table not present\n");
-- 
2.43.0