[S390] mm: fix storage key handling

page_get_storage_key() and page_set_storage_key() expect a page address
and not its page frame number. This got inconsistent with 2d42552d
"[S390] merge page_test_dirty and page_clear_dirty".

Result is that we read/write storage keys from random pages and do not
have a working dirty bit tracking at all.
E.g. SetPageUpdate() doesn't clear the dirty bit of requested pages, which
for example ext4 doesn't like very much and panics after a while.

Unable to handle kernel paging request at virtual user address (null)
Oops: 0004 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Modules linked in:
CPU: 1 Not tainted 2.6.39-07551-g139f37f-dirty #152
Process flush-94:0 (pid: 1576, task: 000000003eb34538, ksp: 000000003c287b70)
Krnl PSW : 0704c00180000000 0000000000316b12 (jbd2_journal_file_inode+0x10e/0x138)
R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 EA:3
Krnl GPRS: 0000000000000000 0000000000000000 0000000000000000 0700000000000000
0000000000316a62 000000003eb34cd0 0000000000000025 000000003c287b88
0000000000000001 000000003c287a70 000000003f1ec678 000000003f1ec000
0000000000000000 000000003e66ec00 0000000000316a62 000000003c287988
Krnl Code: 0000000000316b04: f0a0000407f4 srp 4(11,%r0),2036,0
0000000000316b0a: b9020022 ltgr %r2,%r2
0000000000316b0e: a7740015 brc 7,316b38
>0000000000316b12: e3d0c0000024 stg %r13,0(%r12)
0000000000316b18: 4120c010 la %r2,16(%r12)
0000000000316b1c: 4130d060 la %r3,96(%r13)
0000000000316b20: e340d0600004 lg %r4,96(%r13)
0000000000316b26: c0e50002b567 brasl %r14,36d5f4
Call Trace:
([<0000000000316a62>] jbd2_journal_file_inode+0x5e/0x138)
[<00000000002da13c>] mpage_da_map_and_submit+0x2e8/0x42c
[<00000000002daac2>] ext4_da_writepages+0x2da/0x504
[<00000000002597e8>] writeback_single_inode+0xf8/0x268
[<0000000000259f06>] writeback_sb_inodes+0xd2/0x18c
[<000000000025a700>] writeback_inodes_wb+0x80/0x168
[<000000000025aa92>] wb_writeback+0x2aa/0x324
[<000000000025abde>] wb_do_writeback+0xd2/0x274
[<000000000025ae3a>] bdi_writeback_thread+0xba/0x1c4
[<00000000001737be>] kthread+0xa6/0xb0
[<000000000056c1da>] kernel_thread_starter+0x6/0xc
[<000000000056c1d4>] kernel_thread_starter+0x0/0xc
INFO: lockdep is turned off.
Last Breaking-Event-Address:
[<0000000000316a8a>] jbd2_journal_file_inode+0x86/0x138

Reported-by: Sebastian Ott <[e-mail]>
Signed-off-by: Heiko Carstens <[e-mail]>

arch/s390/include/asm/pgtable.h

···
 static inline pgste_t pgste_update_all(pte_t *ptep, pgste_t pgste)
 {
 #ifdef CONFIG_PGSTE
-	unsigned long pfn, bits;
+	unsigned long address, bits;
 	unsigned char skey;
 
-	pfn = pte_val(*ptep) >> PAGE_SHIFT;
-	skey = page_get_storage_key(pfn);
+	address = pte_val(*ptep) & PAGE_MASK;
+	skey = page_get_storage_key(address);
 	bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
 	/* Clear page changed & referenced bit in the storage key */
 	if (bits) {
 		skey ^= bits;
-		page_set_storage_key(pfn, skey, 1);
+		page_set_storage_key(address, skey, 1);
 	}
 	/* Transfer page changed & referenced bit to guest bits in pgste */
 	pgste_val(pgste) |= bits << 48;		/* RCP_GR_BIT & RCP_GC_BIT */
···
 static inline void pgste_set_pte(pte_t *ptep, pgste_t pgste)
 {
 #ifdef CONFIG_PGSTE
-	unsigned long pfn;
+	unsigned long address;
 	unsigned long okey, nkey;
 
-	pfn = pte_val(*ptep) >> PAGE_SHIFT;
-	okey = nkey = page_get_storage_key(pfn);
+	address = pte_val(*ptep) & PAGE_MASK;
+	okey = nkey = page_get_storage_key(address);
 	nkey &= ~(_PAGE_ACC_BITS | _PAGE_FP_BIT);
 	/* Set page access key and fetch protection bit from pgste */
 	nkey |= (pgste_val(pgste) & (RCP_ACC_BITS | RCP_FP_BIT)) >> 56;
 	if (okey != nkey)
-		page_set_storage_key(pfn, nkey, 1);
+		page_set_storage_key(address, nkey, 1);
 #endif
 }
 

include/linux/page-flags.h

···
 {
 #ifdef CONFIG_S390
 	if (!test_and_set_bit(PG_uptodate, &page->flags))
-		page_set_storage_key(page_to_pfn(page), PAGE_DEFAULT_KEY, 0);
+		page_set_storage_key(page_to_phys(page), PAGE_DEFAULT_KEY, 0);
 #else
 	/*
 	 * Memory barrier must be issued before setting the PG_uptodate bit,