From: Gerald Schaefer <gerald.schaefer@linux.ibm.com>

Subject: s390/kdump: fix out-of-memory with PCI

Patch-mainline: never, fixed upstream with larger code rework

References: bsc#1182257 LTC#191375

Description:   s390/kdump: fix out-of-memory with PCI

Symptom:       The kdump kernel runs out of memory when allocating memory for

               PCI IOMMU bitmaps in zpci_dma_init_device().

Problem:       The kdump kernel does not properly restrict memory_end, which

               the PCI code uses to calculate the size of the IOMMU bitmap, and

               too much memory will be allocated.

Solution:      Properly restrict memory_end to the available memory of the

               kdump kernel (OLDMEM_SIZE), similar to how it would be done with

               a "mem=" kernel parameter.

               This was fixed inadvertently by an unrelated upstream commit

               73045a08cf55 ("s390: unify identity mapping limits handling").

               But that commit cannot easily be backported to distribution

               levels, so only the part that fixes this bug will be submitted.

Reproduction:  Try kdump on a system with large memory size and many PCI

               functions.

Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>

Acked-by: Petr Tesarik <ptesarik@suse.com>

---

 arch/s390/boot/ipl_parm.c |    2 ++

 1 file changed, 2 insertions(+)

--- a/arch/s390/boot/ipl_parm.c

+++ b/arch/s390/boot/ipl_parm.c

@@ -243,6 +243,8 @@ void setup_memory_end(void)

 #ifdef CONFIG_CRASH_DUMP

 	if (OLDMEM_BASE) {

 		kaslr_enabled = 0;

+		memory_end = min(memory_end ?: OLDMEM_SIZE, OLDMEM_SIZE);

+		memory_end_set = 1;

 	} else if (ipl_block_valid &&

 		   ipl_block.pb0_hdr.pbt == IPL_PBT_FCP &&

 		   ipl_block.fcp.opt == IPL_PB0_FCP_OPT_DUMP) {