From c40c48e5d1ef3b7d163eef1bc62d63ffac9a2dff Mon Sep 17 00:00:00 2001 From: Michael Holzheu Date: Thu, 17 Nov 2011 10:41:47 +1100 Subject: [PATCH] kdump: add missing RAM resource in crash_shrink_memory() When shrinking crashkernel memory using /sys/kernel/kexec_crash_size for the newly added memory no RAM resource is created at the moment. Example: $ cat /proc/iomem 00000000-bfffffff : System RAM 00000000-005b7ac3 : Kernel code 005b7ac4-009743bf : Kernel data 009bb000-00a85c33 : Kernel bss c0000000-cfffffff : Crash kernel d0000000-ffffffff : System RAM $ echo 0 > /sys/kernel/kexec_crash_size $ cat /proc/iomem 00000000-bfffffff : System RAM 00000000-005b7ac3 : Kernel code 005b7ac4-009743bf : Kernel data 009bb000-00a85c33 : Kernel bss <<-- here is System RAM missing d0000000-ffffffff : System RAM One result of this bug is that the memory chunk can never be set offline using memory hotplug. With this patch I insert a new "System RAM" resource for the released memory. Then the upper example looks like the following: $ echo 0 > /sys/kernel/kexec_crash_size $ cat /proc/iomem 00000000-bfffffff : System RAM 00000000-005b7ac3 : Kernel code 005b7ac4-009743bf : Kernel data 009bb000-00a85c33 : Kernel bss c0000000-cfffffff : System RAM <<-- new rescoure d0000000-ffffffff : System RAM And now I can set chunk c0000000-cfffffff offline. Signed-off-by: Michael Holzheu Cc: Vivek Goyal Cc: "Eric W. Biederman" Cc: Heiko Carstens Cc: Martin Schwidefsky Signed-off-by: Andrew Morton --- kernel/kexec.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/kernel/kexec.c b/kernel/kexec.c index dc7bc0829286..a779003967b3 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -1132,6 +1132,7 @@ int crash_shrink_memory(unsigned long new_size) { int ret = 0; unsigned long start, end; + struct resource *ram_res; mutex_lock(&kexec_mutex); @@ -1149,6 +1150,12 @@ int crash_shrink_memory(unsigned long new_size) goto unlock; } + ram_res = kzalloc(sizeof(*ram_res), GFP_KERNEL); + if (!ram_res) { + ret = -ENOMEM; + goto unlock; + } + start = roundup(start, KEXEC_CRASH_MEM_ALIGN); end = roundup(start + new_size, KEXEC_CRASH_MEM_ALIGN); @@ -1157,7 +1164,15 @@ int crash_shrink_memory(unsigned long new_size) if ((start == end) && (crashk_res.parent != NULL)) release_resource(&crashk_res); + + ram_res->start = end; + ram_res->end = crashk_res.end; + ram_res->flags = IORESOURCE_BUSY | IORESOURCE_MEM; + ram_res->name = "System RAM"; + crashk_res.end = end - 1; + + insert_resource(&iomem_resource, ram_res); crash_unmap_reserved_pages(); unlock: -- 2.39.5