+ crash-use-macro-to-add-crashk_res-into-iomem-early-for-specific-arch.patch added to mm-hotfixes-unstable branch

+ crash-use-macro-to-add-crashk_res-into-iomem-early-for-specific-arch.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: crash: use macro to add crashk_res into iomem early for specific arch
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     crash-use-macro-to-add-crashk_res-into-iomem-early-for-specific-arch.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/crash-use-macro-to-add-crashk_res-into-iomem-early-for-specific-arch.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Baoquan He <bhe@redhat.com>
Subject: crash: use macro to add crashk_res into iomem early for specific arch
Date: Mon, 25 Mar 2024 09:50:50 +0800

There are regression reports[1][2] that crashkernel region on x86_64 can't
be added into iomem tree sometime.  This causes the later failure of kdump
loading.

This happened after commit 4a693ce65b18 ("kdump: defer the insertion of
crashkernel resources") was merged.

Even though, these reported issues are proved to be related to other
component, they are just exposed after above commmit applied, I still
would like to keep crashk_res and crashk_low_res being added into iomem
early as before because the early adding has been always there on x86_64
and working very well.  For safety of kdump, Let's change it back.

Here, add a macro HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY to limit that
only ARCH defining the macro can have the early adding
crashk_res/_low_res into iomem. Then define
HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY on x86 to enable it.

Note: In reserve_crashkernel_low(), there's a remnant of crashk_low_res
handling which was mistakenly added back in commit 85fcde402db1 ("kexec:
split crashkernel reservation code out from crash_core.c").

[1]
[PATCH V2] x86/kexec: do not update E820 kexec table for setup_data
https://lore.kernel.org/all/Zfv8iCL6CT2JqLIC@darkstar.users.ipa.redhat.com/T/#u

[2]
Question about Address Range Validation in Crash Kernel Allocation
https://lore.kernel.org/all/4eeac1f733584855965a2ea62fa4da58@huawei.com/T/#u

Link: https://lkml.kernel.org/r/ZgDYemRQ2jxjLkq+@MiWiFi-R3L-srv
Fixes: 4a693ce65b18 ("kdump: defer the insertion of crashkernel resources")
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Huacai Chen <chenhuacai@loongson.cn>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/x86/include/asm/crash_reserve.h |    2 ++
 kernel/crash_reserve.c               |    7 +++++++
 2 files changed, 9 insertions(+)

--- a/arch/x86/include/asm/crash_reserve.h~crash-use-macro-to-add-crashk_res-into-iomem-early-for-specific-arch
+++ a/arch/x86/include/asm/crash_reserve.h
@@ -39,4 +39,6 @@ static inline unsigned long crash_low_si
 #endif
 }
 
+#define HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY
+
 #endif /* _X86_CRASH_RESERVE_H */
--- a/kernel/crash_reserve.c~crash-use-macro-to-add-crashk_res-into-iomem-early-for-specific-arch
+++ a/kernel/crash_reserve.c
@@ -366,8 +366,10 @@ static int __init reserve_crashkernel_lo
 
 	crashk_low_res.start = low_base;
 	crashk_low_res.end   = low_base + low_size - 1;
+#ifdef HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY
 	insert_resource(&iomem_resource, &crashk_low_res);
 #endif
+#endif
 	return 0;
 }
 
@@ -448,8 +450,12 @@ retry:
 
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
+#ifdef HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY
+	insert_resource(&iomem_resource, &crashk_res);
+#endif
 }
 
+#ifndef HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY
 static __init int insert_crashkernel_resources(void)
 {
 	if (crashk_res.start < crashk_res.end)
@@ -462,3 +468,4 @@ static __init int insert_crashkernel_res
 }
 early_initcall(insert_crashkernel_resources);
 #endif
+#endif
_

Patches currently in -mm which might be from bhe@redhat.com are

crash-use-macro-to-add-crashk_res-into-iomem-early-for-specific-arch.patch
mm-vmallocc-optimize-to-reduce-arguments-of-alloc_vmap_area.patch
x86-remove-unneeded-memblock_find_dma_reserve.patch
mm-mm_initc-remove-the-useless-dma_reserve.patch
mm-mm_initc-add-new-function-calc_nr_all_pages.patch
mm-mm_initc-remove-meaningless-calculation-of-zone-managed_pages-in-free_area_init_core.patch
mm-mm_initc-remove-unneeded-calc_memmap_size.patch
mm-mm_initc-remove-arch_reserved_kernel_pages.patch