MIPS: TXx9: Fix boot crash in free_initmem() [Linux 5.2]

MIPS: TXx9: Fix boot crash in free_initmem() [Linux 5.2]

This Linux kernel change "MIPS: TXx9: Fix boot crash in free_initmem()" is included in the Linux 5.2 release. This change is authored by Geert Uytterhoeven <geert [at] linux-m68k.org> on Wed May 22 10:15:35 2019 +0200. The commit for this change in Linux stable tree is c5eac1f (patch).

MIPS: TXx9: Fix boot crash in free_initmem()

On rbtx4927:

    BUG: Bad page state in process swapper  pfn:00001
    page:804b7820 refcount:0 mapcount:-128 mapping:00000000 index:0x1
    flags: 0x0()
    raw: 00000000 00000100 00000200 00000000 00000001 00000000 ffffff7f 00000000
    page dumped because: nonzero mapcount
    Modules linked in:
    CPU: 0 PID: 1 Comm: swapper Not tainted 5.2.0-rc1-rbtx4927-00468-g3c05ea3d4077b756 #141
    Stack : 00000000 10008400 8040dc4c 87c1b974 8044af63 8040dc4c 00000001 804a3490
            00000001 81000000 0030f231 80148558 00000003 10008400 87c1dd80 3d0f9a2c
            00000000 00000000 804b0000 00000000 00000007 00000000 00000081 00000000
            62722d31 00000080 804b0000 39347874 00000000 804b7820 8040ce18 81000010
            00000001 00000007 00000001 81000000 00000018 8021de24 00000000 804a0000
            ...
    Call Trace:
    [<8010adec>] show_stack+0x74/0x104
    [<801a5e44>] bad_page+0x130/0x138
    [<801a654c>] free_pcppages_bulk+0x17c/0x3b0
    [<801a789c>] free_unref_page+0x40/0x68
    [<801120f4>] free_init_pages+0xec/0x104
    [<803bdde8>] free_initmem+0x10/0x58
    [<803bdb8c>] kernel_init+0x20/0x100
    [<801057c8>] ret_from_kernel_thread+0x14/0x1c

As of commit b93ddc4f9156205e ("mips: Reserve memory for the kernel
image resources"), bootmem_init() no longer reserves the memory below
the kernel, while prom_free_prom_memory() still frees it.

Fix this by reverting commit b6263ff2d6e58cc2 ("MIPS: TXx9: Implement
prom_free_prom_memory").

Suggested-by: Serge Semin <[email protected]>
Fixes: b93ddc4f9156205e ("mips: Reserve memory for the kernel image resources")
Signed-off-by: Geert Uytterhoeven <[email protected]>
Reviewed-by: Atsushi Nemoto <[email protected]>
Signed-off-by: Paul Burton <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Maciej W . Rozycki <[email protected]>
Cc: [email protected]
Cc: [email protected]

There are 6 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 arch/mips/txx9/generic/setup.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/mips/txx9/generic/setup.c b/arch/mips/txx9/generic/setup.c
index 46537c2..6d0fd0e 100644
--- a/arch/mips/txx9/generic/setup.c
+++ b/arch/mips/txx9/generic/setup.c
@@ -33,7 +33,6 @@
 #include <asm/time.h>
 #include <asm/reboot.h>
 #include <asm/r4kcache.h>
-#include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/txx9/generic.h>
 #include <asm/txx9/pci.h>
@@ -343,11 +342,6 @@ void __init prom_init(void)

 void __init prom_free_prom_memory(void)
 {
-   unsigned long saddr = PAGE_SIZE;
-   unsigned long eaddr = __pa_symbol(&_text);
-
-   if (saddr < eaddr)
-       free_init_pages("prom memory", saddr, eaddr);
 }

 const char *get_system_type(void)

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