linux-kernel - [RFC PATCH for 4.21 03/16] mm: Replace BUG_ON() by WARN_ON() in vm_unmap

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Date:   Thu,  1 Nov 2018 10:58:31 +0100
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...capital.net>,
        Dave Watson <davejwatson@...com>, Paul Turner <pjt@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Russell King <linux@....linux.org.uk>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Andi Kleen <andi@...stfloor.org>, Chris Lameter <cl@...ux.com>,
        Ben Maurer <bmaurer@...com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Josh Triplett <josh@...htriplett.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>
Subject: [RFC PATCH for 4.21 03/16] mm: Replace BUG_ON() by WARN_ON() in vm_unmap_ram()

It is encouraged to warn and return rather than use BUG_ON() when
the condition can be recovered from in ways that are more graceful than
halting the whole system.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Suggested-by: Steven Rostedt <rostedt@...dmis.org>
CC: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
CC: Matthew Wilcox <mawilcox@...rosoft.com>
CC: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
CC: Peter Zijlstra <peterz@...radead.org>
CC: Paul Turner <pjt@...gle.com>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Andy Lutomirski <luto@...capital.net>
CC: Andi Kleen <andi@...stfloor.org>
CC: Dave Watson <davejwatson@...com>
CC: Chris Lameter <cl@...ux.com>
CC: Ingo Molnar <mingo@...hat.com>
CC: "H. Peter Anvin" <hpa@...or.com>
CC: Ben Maurer <bmaurer@...com>
CC: Steven Rostedt <rostedt@...dmis.org>
CC: Josh Triplett <josh@...htriplett.org>
CC: Linus Torvalds <torvalds@...ux-foundation.org>
CC: Andrew Morton <akpm@...ux-foundation.org>
CC: Russell King <linux@....linux.org.uk>
CC: Catalin Marinas <catalin.marinas@....com>
CC: Will Deacon <will.deacon@....com>
CC: Michael Kerrisk <mtk.manpages@...il.com>
CC: Boqun Feng <boqun.feng@...il.com>
---
 mm/vmalloc.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a728fc492557..a236bac872f0 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1123,10 +1123,11 @@ void vm_unmap_ram(const void *mem, unsigned int count)
 	struct vmap_area *va;
 
 	might_sleep();
-	BUG_ON(!addr);
-	BUG_ON(addr < VMALLOC_START);
-	BUG_ON(addr > VMALLOC_END);
-	BUG_ON(!PAGE_ALIGNED(addr));
+	if (WARN_ON(!addr) ||
+	    WARN_ON(addr < VMALLOC_START) ||
+	    WARN_ON(addr > VMALLOC_END) ||
+	    WARN_ON(!PAGE_ALIGNED(addr)))
+		return;
 
 	if (likely(count <= VMAP_MAX_ALLOC)) {
 		debug_check_no_locks_freed(mem, size);
@@ -1135,7 +1136,8 @@ void vm_unmap_ram(const void *mem, unsigned int count)
 	}
 
 	va = find_vmap_area(addr);
-	BUG_ON(!va);
+	if (WARN_ON(!va))
+		return;
 	debug_check_no_locks_freed((void *)va->va_start,
 				    (va->va_end - va->va_start));
 	free_unmap_vmap_area(va);
-- 
2.11.0