linux-kernel - [PATCH] vmcore: continue vmcore initialization if PT

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Date:	Fri, 21 Mar 2014 11:20:53 +0800
From:	WANG Chao <chaowang@...hat.com>
To:	Vivek Goyal <vgoyal@...hat.com>,
	Greg Pearson <greg.pearson@...com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	HATAYAMA Daisuke <d.hatayama@...fujitsu.com>, bhe@...hat.com
Cc:	kexec@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] vmcore: continue vmcore initialization if PT_NOTE is found empty

Currently when an empty PT_NOTE is detected, vmcore initialization
fails. It sounds too harsh. Because PT_NOTE could be empty, for example,
one offlined a cpu but never restarted kdump service, and after crash,
PT_NOTE program header is there but no data contains. It's better to
warn about the empty PT_NOTE and continue to initialise vmcore.

And ultimately the multiple PT_NOTE are merged into a single one, all
empty PT_NOTE are discarded naturally during the merge. So empty PT_NOTE
is not visible to user space and vmcore is as good as expected.

Signed-off-by: WANG Chao <chaowang@...hat.com>
---
 fs/proc/vmcore.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 88d4585..dc71bf9 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -484,7 +484,6 @@ static int __init update_note_header_size_elf64(const Elf64_Ehdr *ehdr_ptr)
 		phdr_ptr->p_memsz = real_sz;
 		if (real_sz == 0) {
 			pr_warn("Warning: Zero PT_NOTE entries found\n");
-			return -EINVAL;
 		}
 	}
 
@@ -671,7 +670,6 @@ static int __init update_note_header_size_elf32(const Elf32_Ehdr *ehdr_ptr)
 		phdr_ptr->p_memsz = real_sz;
 		if (real_sz == 0) {
 			pr_warn("Warning: Zero PT_NOTE entries found\n");
-			return -EINVAL;
 		}
 	}
 
-- 
1.8.5.3

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