[Devel] [PATCH RHEL8 COMMIT] mm: add __GFP_ flag to hide verified high order allocation warnings

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-80.1.2.vz8.3.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-80.1.2.vz8.3.8
------>
commit 41042c4108fbd0a700124301a21bd815fc69d67e
Author: Andrey Ryabinin <aryabinin at virtuozzo.com>
Date:   Thu Feb 14 17:03:49 2019 +0300

    mm: add __GFP_ flag to hide verified high order allocation warnings
    
    Using __GFP_NOWARN to hide known high order allocation warnings
    is not the best solution as it supresses allocation failures as well,
    so let's add an independent __GFP_ORDER_NOWARN flag for that.
    
    Fixes: 22b422587aab mm: add warning about high order allocations
    
    https://pmc.acronis.com/browse/VSTOR-20383
    https://pmc.acronis.com/browse/VSTOR-20349
    
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
    
    https://jira.sw.ru/browse/PSBM-103814
    
    (cherry picked from commit 66f0d9c1678847ee476af8d511839728d144c83b)
    Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 include/linux/gfp.h | 9 +++++++--
 mm/page_alloc.c     | 3 ++-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index a6afcec53795..90084ff02484 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -39,8 +39,9 @@ struct vm_area_struct;
 #define ___GFP_ACCOUNT		0x100000u
 #define ___GFP_DIRECT_RECLAIM	0x200000u
 #define ___GFP_KSWAPD_RECLAIM	0x400000u
+#define ___GFP_ORDER_NOWARN	0x800000u
 #ifdef CONFIG_LOCKDEP
-#define ___GFP_NOLOCKDEP	0x800000u
+#define ___GFP_NOLOCKDEP	0x1000000u
 #else
 #define ___GFP_NOLOCKDEP	0
 #endif
@@ -196,16 +197,20 @@ struct vm_area_struct;
  * __GFP_COMP address compound page metadata.
  *
  * __GFP_ZERO returns a zeroed page on success.
+ *
+ * __GFP_ORDER_NOWARN suppresses reports about allocation of too high order
+ * pages.
  */
 #define __GFP_NOWARN	((__force gfp_t)___GFP_NOWARN)
 #define __GFP_COMP	((__force gfp_t)___GFP_COMP)
 #define __GFP_ZERO	((__force gfp_t)___GFP_ZERO)
+#define __GFP_ORDER_NOWARN ((__force gfp_t)___GFP_ORDER_NOWARN)
 
 /* Disable lockdep for GFP context tracking */
 #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP)
 
 /* Room for N __GFP_FOO bits */
-#define __GFP_BITS_SHIFT (23 + IS_ENABLED(CONFIG_LOCKDEP))
+#define __GFP_BITS_SHIFT (24 + IS_ENABLED(CONFIG_LOCKDEP))
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /*
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cbd6ee3ed01e..0a47163faa11 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4417,7 +4417,8 @@ 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);