linux-kernel - [PATCH 4.9 2/9] mm: add VM_WARN_ON_ONCE

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Message-Id: <20210709131545.988367954@linuxfoundation.org>
Date:   Fri,  9 Jul 2021 15:18:29 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alex Shi <alex.shi@...ux.alibaba.com>,
        Michal Hocko <mhocko@...e.com>,
        Hugh Dickins <hughd@...gle.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 2/9] mm: add VM_WARN_ON_ONCE_PAGE() macro

From: Alex Shi <alex.shi@...ux.alibaba.com>

[ Upstream commit a4055888629bc0467d12d912cd7c90acdf3d9b12 part ]

Add VM_WARN_ON_ONCE_PAGE() macro.

Link: https://lkml.kernel.org/r/1604283436-18880-3-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi <alex.shi@...ux.alibaba.com>
Acked-by: Michal Hocko <mhocko@...e.com>
Acked-by: Hugh Dickins <hughd@...gle.com>
Acked-by: Johannes Weiner <hannes@...xchg.org>
Cc: Vladimir Davydov <vdavydov.dev@...il.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>

Note on stable backport: original commit was titled
mm/memcg: warning on !memcg after readahead page charged
which included uses of this macro in mm/memcontrol.c: here omitted.

Signed-off-by: Hugh Dickins <hughd@...gle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/linux/mmdebug.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index deaba1cc3cfc..d1fb3bbff37a 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -36,6 +36,18 @@ void dump_mm(const struct mm_struct *mm);
 			BUG();						\
 		}							\
 	} while (0)
+#define VM_WARN_ON_ONCE_PAGE(cond, page)	({			\
+	static bool __section(".data.once") __warned;			\
+	int __ret_warn_once = !!(cond);					\
+									\
+	if (unlikely(__ret_warn_once && !__warned)) {			\
+		dump_page(page, "VM_WARN_ON_ONCE_PAGE(" __stringify(cond)")");\
+		__warned = true;					\
+		WARN_ON(1);						\
+	}								\
+	unlikely(__ret_warn_once);					\
+})
+
 #define VM_WARN_ON(cond) (void)WARN_ON(cond)
 #define VM_WARN_ON_ONCE(cond) (void)WARN_ON_ONCE(cond)
 #define VM_WARN_ONCE(cond, format...) (void)WARN_ONCE(cond, format)
@@ -47,6 +59,7 @@ void dump_mm(const struct mm_struct *mm);
 #define VM_BUG_ON_MM(cond, mm) VM_BUG_ON(cond)
 #define VM_WARN_ON(cond) BUILD_BUG_ON_INVALID(cond)
 #define VM_WARN_ON_ONCE(cond) BUILD_BUG_ON_INVALID(cond)
+#define VM_WARN_ON_ONCE_PAGE(cond, page)  BUILD_BUG_ON_INVALID(cond)
 #define VM_WARN_ONCE(cond, format...) BUILD_BUG_ON_INVALID(cond)
 #define VM_WARN(cond, format...) BUILD_BUG_ON_INVALID(cond)
 #endif
-- 
2.30.2