linux-kernel - [tip:x86/kdump] swiotlb: Warn on allocation failure in swiotlb_alloc

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Date:	Fri, 12 Jun 2015 01:49:56 -0700
From:	tip-bot for Joerg Roedel <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, jroedel@...e.de, bp@...e.de,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	hpa@...or.com, dyoung@...hat.com, joro@...tes.org,
	peterz@...radead.org, tglx@...utronix.de, konrad.wilk@...cle.com,
	brgerst@...il.com, luto@...capital.net, dvlasenk@...hat.com,
	mingo@...nel.org, bp@...en8.de, vgoyal@...hat.com, bhe@...hat.com
Subject: [tip:x86/kdump] swiotlb:
  Warn on allocation failure in swiotlb_alloc_coherent()

Commit-ID:  94cc81f9a8f995923e35e2db936741dd62d18350
Gitweb:     http://git.kernel.org/tip/94cc81f9a8f995923e35e2db936741dd62d18350
Author:     Joerg Roedel <jroedel@...e.de>
AuthorDate: Wed, 10 Jun 2015 17:49:40 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 11 Jun 2015 08:28:38 +0200

swiotlb: Warn on allocation failure in swiotlb_alloc_coherent()

Print a warning when all allocation tries have been failed
and the function is about to return NULL.

This prepares for calling the function with __GFP_NOWARN to
suppress allocation failure warnings before all fall-backs
have failed - which we'll do to improve kdump behavior.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Borislav Petkov <bp@...e.de>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Acked-by: Baoquan He <bhe@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Young <dyoung@...hat.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Jörg Rödel <joro@...tes.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vivek Goyal <vgoyal@...hat.com>
Cc: kexec@...ts.infradead.org
Link: http://lkml.kernel.org/r/1433500202-25531-2-git-send-email-joro@8bytes.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 lib/swiotlb.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 3c365ab..42e192d 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -656,7 +656,7 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 		 */
 		phys_addr_t paddr = map_single(hwdev, 0, size, DMA_FROM_DEVICE);
 		if (paddr == SWIOTLB_MAP_ERROR)
-			return NULL;
+			goto err_warn;
 
 		ret = phys_to_virt(paddr);
 		dev_addr = phys_to_dma(hwdev, paddr);
@@ -670,7 +670,7 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 			/* DMA_TO_DEVICE to avoid memcpy in unmap_single */
 			swiotlb_tbl_unmap_single(hwdev, paddr,
 						 size, DMA_TO_DEVICE);
-			return NULL;
+			goto err_warn;
 		}
 	}
 
@@ -678,6 +678,13 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 	memset(ret, 0, size);
 
 	return ret;
+
+err_warn:
+	pr_warn("swiotlb: coherent allocation failed for device %s size=%zu\n",
+		dev_name(hwdev), size);
+	dump_stack();
+
+	return NULL;
 }
 EXPORT_SYMBOL(swiotlb_alloc_coherent);
 
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