linux-kernel - RE: [RFC Patch 1/2] kexec: show memory info in /proc/iomem

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Date:	Tue, 11 Aug 2009 13:50:50 -0700
From:	"Yu, Fenghua" <fenghua.yu@...el.com>
To:	'Amerigo Wang' <amwang@...hat.com>,
	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>
CC:	"'linux-ia64@...r.kernel.org'" <linux-ia64@...r.kernel.org>,
	'Neil Horman' <nhorman@...hat.com>,
	"'Eric W. Biederman'" <ebiederm@...ssion.com>,
	'Andi Kleen' <andi@...stfloor.org>,
	"'akpm@...ux-foundation.org'" <akpm@...ux-foundation.org>,
	'Ingo Molnar' <mingo@...e.hu>
Subject: RE: [RFC Patch 1/2] kexec: show memory info in /proc/iomem

>
>---
>diff --git a/kernel/kexec.c b/kernel/kexec.c
>index f336e21..01673ad 100644
>--- a/kernel/kexec.c
>+++ b/kernel/kexec.c
>@@ -931,6 +931,8 @@ static int kimage_load_segment(struct kimage *image,
>  */
> struct kimage *kexec_image;
> struct kimage *kexec_crash_image;
>+struct resource *kexec_res = NULL;
>+struct resource *kexec_free_res = NULL;
>
> static DEFINE_MUTEX(kexec_mutex);
>
>@@ -939,6 +941,8 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry,
>unsigned long, nr_segments,
> {
> 	struct kimage **dest_image, *image;
> 	int result;
>+	unsigned long kexec_start = crashk_res.start;
>+	unsigned long kexec_end = kexec_start;
>
> 	/* We only trust the superuser with rebooting the system. */
> 	if (!capable(CAP_SYS_BOOT))
>@@ -994,6 +998,7 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry,
>unsigned long, nr_segments,
> 			kimage_free(xchg(&kexec_crash_image, NULL));
> 			result = kimage_crash_alloc(&image, entry,
> 						     nr_segments, segments);
>+			kexec_end += KEXEC_CONTROL_PAGE_SIZE;
> 		}
> 		if (result)
> 			goto out;
>@@ -1008,6 +1013,42 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry,
>unsigned long, nr_segments,
> 			result = kimage_load_segment(image, &image->segment[i]);
> 			if (result)
> 				goto out;
>+			if (flags & KEXEC_ON_CRASH)
>+				kexec_end += image->segment[i].memsz;
>+		}
>+		if (flags & KEXEC_ON_CRASH) {
>+			if (kexec_res) {
>+				release_resource(kexec_res);
>+				release_resource(kexec_free_res);
>+				kfree(kexec_res);
>+				kfree(kexec_free_res);
>+			}
>+			kexec_res = kzalloc(sizeof(*kexec_res), GFP_KERNEL);
>+			if (!kexec_res) {
>+				result = -ENOMEM;
>+				goto out;
>+			}
>+			kexec_free_res = kzalloc(sizeof(*kexec_free_res),
>GFP_KERNEL);
>+			if (!kexec_free_res) {
>+				result = -ENOMEM;
>+				goto out_free;
>+			}
>+			kexec_res->name = "Used";
>+			kexec_res->start = kexec_start;
>+			kexec_res->end = roundup(kexec_end, 1<<20) - 1;
>+			kexec_res->flags = IORESOURCE_BUSY | IORESOURCE_MEM;
>+			if (insert_resource(&crashk_res, kexec_res)) {
>+				result = -EBUSY;
>+				goto out_free;
>+			}
>+			kexec_free_res->name = "Unused";
>+			kexec_free_res->start = kexec_res->end + 1;
>+			kexec_free_res->end = crashk_res.end;
>+			kexec_free_res->flags = IORESOURCE_BUSY | IORESOURCE_MEM;
>+			if (insert_resource(&crashk_res, kexec_free_res)) {
>+				result = -EBUSY;
>+				goto out_release;
>+			}
> 		}
> 		kimage_terminate(image);
> 	}
>@@ -1019,6 +1060,13 @@ out:
> 	kimage_free(image);
>
> 	return result;
>+
>+out_free:
>+	kfree(kexec_free_res);
>+	kfree(kexec_res);
>+out_release:
>+	release_resource(kexec_res);
>+	goto out;
> }

The order of out_free: and out_release: might be reversed. You need to release_resource first; then kfree. Otherwise the previous failures jump to here and will cause problem.

Thanks.

-Fenghua
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