6.18-stable review patch. If anyone has any objections, please let me know.
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From: Sourabh Jain sourabhjain@linux.ibm.com
commit adc15829fb73e402903b7030729263b6ee4a7232 upstream.
With the generic crashkernel reservation, the kernel emits the following warning on powerpc:
WARNING: CPU: 0 PID: 1 at arch/powerpc/mm/mem.c:341 add_system_ram_resources+0xfc/0x180 Modules linked in: CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.17.0-auto-12607-g5472d60c129f #1 VOLUNTARY Hardware name: IBM,9080-HEX Power11 (architected) 0x820200 0xf000007 of:IBM,FW1110.01 (NH1110_069) hv:phyp pSeries NIP: c00000000201de3c LR: c00000000201de34 CTR: 0000000000000000 REGS: c000000127cef8a0 TRAP: 0700 Not tainted (6.17.0-auto-12607-g5472d60c129f) MSR: 8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 84000840 XER: 20040010 CFAR: c00000000017eed0 IRQMASK: 0 GPR00: c00000000201de34 c000000127cefb40 c0000000016a8100 0000000000000001 GPR04: c00000012005aa00 0000000020000000 c000000002b705c8 0000000000000000 GPR08: 000000007fffffff fffffffffffffff0 c000000002db8100 000000011fffffff GPR12: c00000000201dd40 c000000002ff0000 c0000000000112bc 0000000000000000 GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR20: 0000000000000000 0000000000000000 0000000000000000 c0000000015a3808 GPR24: c00000000200468c c000000001699888 0000000000000106 c0000000020d1950 GPR28: c0000000014683f8 0000000081000200 c0000000015c1868 c000000002b9f710 NIP [c00000000201de3c] add_system_ram_resources+0xfc/0x180 LR [c00000000201de34] add_system_ram_resources+0xf4/0x180 Call Trace: add_system_ram_resources+0xf4/0x180 (unreliable) do_one_initcall+0x60/0x36c do_initcalls+0x120/0x220 kernel_init_freeable+0x23c/0x390 kernel_init+0x34/0x26c ret_from_kernel_user_thread+0x14/0x1c
This warning occurs due to a conflict between crashkernel and System RAM iomem resources.
The generic crashkernel reservation adds the crashkernel memory range to /proc/iomem during early initialization. Later, all memblock ranges are added to /proc/iomem as System RAM. If the crashkernel region overlaps with any memblock range, it causes a conflict while adding those memblock regions as iomem resources, triggering the above warning. The conflicting memblock regions are then omitted from /proc/iomem.
For example, if the following crashkernel region is added to /proc/iomem: 20000000-11fffffff : Crash kernel
then the following memblock regions System RAM regions fail to be inserted: 00000000-7fffffff : System RAM 80000000-257fffffff : System RAM
Fix this by not adding the crashkernel memory to /proc/iomem on powerpc. Introduce an architecture hook to let each architecture decide whether to export the crashkernel region to /proc/iomem.
For more info checkout commit c40dd2f766440 ("powerpc: Add System RAM to /proc/iomem") and commit bce074bdbc36 ("powerpc: insert System RAM resource to prevent crashkernel conflict")
Note: Before switching to the generic crashkernel reservation, powerpc never exported the crashkernel region to /proc/iomem.
Link: https://lkml.kernel.org/r/20251016142831.144515-1-sourabhjain@linux.ibm.com Fixes: e3185ee438c2 ("powerpc/crash: use generic crashkernel reservation"). Signed-off-by: Sourabh Jain sourabhjain@linux.ibm.com Reported-by: Venkat Rao Bagalkote venkat88@linux.ibm.com Closes: https://lore.kernel.org/all/90937fe0-2e76-4c82-b27e-7b8a7fe3ac69@linux.ibm.c... Tested-by: Venkat Rao Bagalkote venkat88@linux.ibm.com Cc: Baoquan he bhe@redhat.com Cc: Hari Bathini hbathini@linux.ibm.com Cc: Madhavan Srinivasan maddy@linux.ibm.com Cc: Mahesh Salgaonkar mahesh@linux.ibm.com Cc: Michael Ellerman mpe@ellerman.id.au Cc: Ritesh Harjani (IBM) ritesh.list@gmail.com Cc: Vivek Goyal vgoyal@redhat.com Cc: Dave Young dyoung@redhat.com Cc: Mike Rapoport rppt@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/include/asm/crash_reserve.h | 8 ++++++++ include/linux/crash_reserve.h | 6 ++++++ kernel/crash_reserve.c | 3 +++ 3 files changed, 17 insertions(+)
diff --git a/arch/powerpc/include/asm/crash_reserve.h b/arch/powerpc/include/asm/crash_reserve.h index 6467ce29b1fa..d1b570ddbf98 100644 --- a/arch/powerpc/include/asm/crash_reserve.h +++ b/arch/powerpc/include/asm/crash_reserve.h @@ -5,4 +5,12 @@ /* crash kernel regions are Page size agliged */ #define CRASH_ALIGN PAGE_SIZE
+#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION +static inline bool arch_add_crash_res_to_iomem(void) +{ + return false; +} +#define arch_add_crash_res_to_iomem arch_add_crash_res_to_iomem +#endif + #endif /* _ASM_POWERPC_CRASH_RESERVE_H */ diff --git a/include/linux/crash_reserve.h b/include/linux/crash_reserve.h index 7b44b41d0a20..f0dc03d94ca2 100644 --- a/include/linux/crash_reserve.h +++ b/include/linux/crash_reserve.h @@ -32,6 +32,12 @@ int __init parse_crashkernel(char *cmdline, unsigned long long system_ram, void __init reserve_crashkernel_cma(unsigned long long cma_size);
#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION +#ifndef arch_add_crash_res_to_iomem +static inline bool arch_add_crash_res_to_iomem(void) +{ + return true; +} +#endif #ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE #define DEFAULT_CRASH_KERNEL_LOW_SIZE (128UL << 20) #endif diff --git a/kernel/crash_reserve.c b/kernel/crash_reserve.c index 87bf4d41eabb..62e60e0223cf 100644 --- a/kernel/crash_reserve.c +++ b/kernel/crash_reserve.c @@ -524,6 +524,9 @@ void __init reserve_crashkernel_cma(unsigned long long cma_size) #ifndef HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY static __init int insert_crashkernel_resources(void) { + if (!arch_add_crash_res_to_iomem()) + return 0; + if (crashk_res.start < crashk_res.end) insert_resource(&iomem_resource, &crashk_res);