[Devel] [PATCH rh7] x86/pci-dma: don't warn about high order in dma_alloc

[Andrey Ryabinin]

dma_generic_alloc_coherent() requires physically contiguous memory,
hence there is no point in warning about high-order since we can't
do anything about it:

WARNING: CPU: 2 PID: 2072 at mm/page_alloc.c:3530 __alloc_pages_nodemask+0x311/0x610
order 3 >= 3, gfp 0x80d0

Call Trace:
 dump_stack+0x19/0x1b
 __warn+0xd8/0x100
 warn_slowpath_fmt+0x5f/0x80
 __alloc_pages_nodemask+0x311/0x610
 dma_generic_alloc_coherent+0x8f/0x140
 x86_swiotlb_alloc_coherent+0x21/0x50
 ocrdma_alloc_q.isra.36+0xb6/0x110 [ocrdma]
 ocrdma_init_hw+0x5bc/0x1520 [ocrdma]
 ocrdma_add+0xe2/0x800 [ocrdma]
 _be_roce_dev_add+0x18c/0x200 [be2net]
 be_roce_register_driver+0x48/0x90 [be2net]
 ocrdma_init_module+0x4a/0x1000 [ocrdma]
 do_one_initcall+0xba/0x240
 load_module+0x2796/0x2f50
 SyS_init_module+0xef/0x140
 system_call_fastpath+0x22/0x27

Add and use __GFP_ORDER_NOWARN to hide these warnings

https://pmc.acronis.com/browse/VSTOR-20383
https://pmc.acronis.com/browse/VSTOR-20349
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 arch/x86/kernel/pci-dma.c | 2 +-
 include/linux/gfp.h       | 2 ++
 mm/page_alloc.c           | 3 ++-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 77a4e6222434..e0c605397a42 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -99,7 +99,7 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size,
 
 	dma_mask = dma_alloc_coherent_mask(dev, flag);
 
-	flag |= __GFP_ZERO;
+	flag |= __GFP_ZERO | __GFP_ORDER_NOWARN;
 again:
 	page = NULL;
 	/* CMA can be used only in the context which permits sleeping */
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index c34ba0fa51d8..237596e6ce42 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -41,6 +41,7 @@ struct vm_area_struct;
 #define ___GFP_NO_KSWAPD	0x400000u
 #define ___GFP_OTHER_NODE	0x800000u
 #define ___GFP_WRITE		0x1000000u
+#define ___GFP_ORDER_NOWARN	0x2000000u
 /* If the above are modified, __GFP_BITS_SHIFT may need updating */
 
 /*
@@ -98,6 +99,7 @@ struct vm_area_struct;
 #define __GFP_NO_KSWAPD	((__force gfp_t)___GFP_NO_KSWAPD)
 #define __GFP_OTHER_NODE ((__force gfp_t)___GFP_OTHER_NODE) /* On behalf of other node */
 #define __GFP_WRITE	((__force gfp_t)___GFP_WRITE)	/* Allocator intends to dirty page */
+#define __GFP_ORDER_NOWARN ((__force gfp_t)___GFP_ORDER_NOWARN)
 
 /*
  * This may seem redundant, but it's a way of annotating false positives vs.
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 109011311e6d..74395116344b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3524,7 +3524,8 @@ static __always_inline void warn_high_order(int order, gfp_t gfp_mask)
 	if (static_key_false(&warn_high_order_key)) {
 		int tmp_warn_order = smp_load_acquire(&warn_order);
 
-		if (order >= tmp_warn_order && !(gfp_mask & __GFP_NOWARN))
+		if (order >= tmp_warn_order &&
+		    !(gfp_mask & (__GFP_NOWARN|__GFP_ORDER_NOWARN)))
 			WARN(atomic_dec_if_positive(&warn_count) >= 0,
 				"order %d >= %d, gfp 0x%x\n",
 				order, tmp_warn_order, gfp_mask);
-- 
2.19.2