From: Baoquan He <bhe@xxxxxxxxxx> 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit eb6db83d105914c246ac5875be76fd4b944833d5 upstream. People reported that when allocating crashkernel memory using the ",high" and ",low" syntax, there were cases where the reservation of the high portion succeeds but the reservation of the low portion fails. Then kexec can load the kdump kernel successfully, but booting the kdump kernel fails as there's no low memory. The low memory allocation for the kdump kernel can fail on large systems for a couple of reasons. For example, the manually specified crashkernel low memory can be too large and thus no adequate memblock region would be found. Therefore, we try to reserve low memory for the crash kernel *after* the high memory portion has been allocated. If that fails, we free crashkernel high memory too and return. The user can then take measures accordingly. Tested-by: Joerg Roedel <jroedel@xxxxxxx> Signed-off-by: Baoquan He <bhe@xxxxxxxxxx> [ Massage text. ] Signed-off-by: Borislav Petkov <bp@xxxxxxx> Reviewed-by: Joerg Roedel <jroedel@xxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Dave Young <dyoung@xxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Jiri Kosina <jkosina@xxxxxxx> Cc: Juergen Gross <jgross@xxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Mark Salter <msalter@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: WANG Chao <chaowang@xxxxxxxxxx> Cc: jerry_hoemann@xxxxxx Cc: yinghai@xxxxxxxxxx Link: http://lkml.kernel.org/r/1445246268-26285-2-git-send-email-bp@xxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- arch/x86/kernel/setup.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 3ebbd1fdc0a8..158c4751fa6c 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -511,7 +511,7 @@ static void __init memblock_x86_reserve_range_setup_data(void) # define CRASH_KERNEL_ADDR_HIGH_MAX MAXMEM #endif -static void __init reserve_crashkernel_low(void) +static int __init reserve_crashkernel_low(void) { #ifdef CONFIG_X86_64 const unsigned long long alignment = 16<<20; /* 16M */ @@ -538,17 +538,16 @@ static void __init reserve_crashkernel_low(void) } else { /* passed with crashkernel=0,low ? */ if (!low_size) - return; + return 0; } low_base = memblock_find_in_range(low_size, (1ULL<<32), low_size, alignment); if (!low_base) { - if (!auto_set) - pr_info("crashkernel low reservation failed - No suitable area found.\n"); - - return; + pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n", + (unsigned long)(low_size >> 20)); + return -ENOMEM; } memblock_reserve(low_base, low_size); @@ -560,6 +559,7 @@ static void __init reserve_crashkernel_low(void) crashk_low_res.end = low_base + low_size - 1; insert_resource(&iomem_resource, &crashk_low_res); #endif + return 0; } static void __init reserve_crashkernel(void) @@ -611,6 +611,11 @@ static void __init reserve_crashkernel(void) } memblock_reserve(crash_base, crash_size); + if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) { + memblock_free(crash_base, crash_size); + return; + } + printk(KERN_INFO "Reserving %ldMB of memory at %ldMB " "for crashkernel (System RAM: %ldMB)\n", (unsigned long)(crash_size >> 20), @@ -620,9 +625,6 @@ static void __init reserve_crashkernel(void) crashk_res.start = crash_base; crashk_res.end = crash_base + crash_size - 1; insert_resource(&iomem_resource, &crashk_res); - - if (crash_base >= (1ULL<<32)) - reserve_crashkernel_low(); } #else static void __init reserve_crashkernel(void) -- 2.6.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html