[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <c1e66d3e69c8d90988c02b84c79db5d9dd93f053.1728386179.git.ritesh.list@gmail.com>
Date: Tue, 8 Oct 2024 18:57:18 +0530
From: "Ritesh Harjani (IBM)" <ritesh.list@...il.com>
To: linuxppc-dev@...ts.ozlabs.org
Cc: linux-mm@...ck.org,
Sourabh Jain <sourabhjain@...ux.ibm.com>,
Hari Bathini <hbathini@...ux.ibm.com>,
Zi Yan <ziy@...dia.com>,
David Hildenbrand <david@...hat.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
Michael Ellerman <mpe@...erman.id.au>,
Madhavan Srinivasan <maddy@...ux.ibm.com>,
"Aneesh Kumar K . V" <aneesh.kumar@...nel.org>,
Donet Tom <donettom@...ux.vnet.ibm.com>,
LKML <linux-kernel@...r.kernel.org>,
"Ritesh Harjani (IBM)" <ritesh.list@...il.com>,
Sachin P Bappalige <sachinpb@...ux.ibm.com>
Subject: [RFC 1/2] cma: Fix CMA_MIN_ALIGNMENT_BYTES during early_init
During early init CMA_MIN_ALIGNMENT_BYTES can be PAGE_SIZE,
since pageblock_order is still zero and it gets initialized
later during paging_init() e.g.
paging_init() -> free_area_init() -> set_pageblock_order().
One such use case is -
early_setup() -> early_init_devtree() -> fadump_reserve_mem()
This causes CMA memory alignment check to be bypassed in
cma_init_reserved_mem(). Then later cma_activate_area() can hit
a VM_BUG_ON_PAGE(pfn & ((1 << order) - 1)) if the reserved memory
area was not pageblock_order aligned.
Instead of fixing it locally for fadump case on PowerPC, I believe
this should be fixed for CMA_MIN_ALIGNMENT_BYTES.
<stack trace>
==============
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10010
flags: 0x13ffff800000000(node=1|zone=0|lastcpupid=0x7ffff) CMA
raw: 013ffff800000000 5deadbeef0000100 5deadbeef0000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: VM_BUG_ON_PAGE(pfn & ((1 << order) - 1))
------------[ cut here ]------------
kernel BUG at mm/page_alloc.c:778!
Call Trace:
__free_one_page+0x57c/0x7b0 (unreliable)
free_pcppages_bulk+0x1a8/0x2c8
free_unref_page_commit+0x3d4/0x4e4
free_unref_page+0x458/0x6d0
init_cma_reserved_pageblock+0x114/0x198
cma_init_reserved_areas+0x270/0x3e0
do_one_initcall+0x80/0x2f8
kernel_init_freeable+0x33c/0x530
kernel_init+0x34/0x26c
ret_from_kernel_user_thread+0x14/0x1c
Reported-by: Sachin P Bappalige <sachinpb@...ux.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@...il.com>
---
include/linux/cma.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/linux/cma.h b/include/linux/cma.h
index 9db877506ea8..20abc6561bcd 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -5,6 +5,7 @@
#include <linux/init.h>
#include <linux/types.h>
#include <linux/numa.h>
+#include <linux/minmax.h>
#ifdef CONFIG_CMA_AREAS
#define MAX_CMA_AREAS CONFIG_CMA_AREAS
@@ -17,7 +18,8 @@
* -- can deal with only some pageblocks of a higher-order page being
* MIGRATE_CMA, we can use pageblock_nr_pages.
*/
-#define CMA_MIN_ALIGNMENT_PAGES pageblock_nr_pages
+#define CMA_MIN_ALIGNMENT_PAGES \
+ (1ULL << min_not_zero(MAX_PAGE_ORDER, pageblock_order))
#define CMA_MIN_ALIGNMENT_BYTES (PAGE_SIZE * CMA_MIN_ALIGNMENT_PAGES)
struct cma;
--
2.46.0
Powered by blists - more mailing lists