linux-kernel - Re: [PATCH] PCI: Tone down resource mmap warning

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Date:   Thu, 30 Nov 2017 09:38:01 +0800
From:   Fengguang Wu <fengguang.wu@...el.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     linux-pci@...r.kernel.org, Dave Jones <davej@...emonkey.org.uk>,
        linux-kernel@...r.kernel.org, David Woodhouse <dwmw@...zon.co.uk>
Subject: Re: [PATCH] PCI: Tone down resource mmap warning

This is perhaps the most clean solution. Thank you for the patch!  -fengguang

On Wed, Nov 29, 2017 at 04:57:08PM -0600, Bjorn Helgaas wrote:
>From: Bjorn Helgaas <bhelgaas@...gle.com>
>
>When a process tries to mmap more space than is available in a PCI BAR, we
>emit a warning and a backtrace.  The mmap fails anyway, so the backtrace is
>mainly for debugging.  It seems like overkill now, so reduce this to a
>dev_info() and remove the backtrace.
>
>This was added by b5ff7df3df9e ("Check mapped ranges on sysfs resource
>files").
>
>Reported-by: Fengguang Wu <fengguang.wu@...el.com>
>Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
>---
> drivers/pci/pci-sysfs.c |    6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
>diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
>index 06c7f0b85cd2..97f071674605 100644
>--- a/drivers/pci/pci-sysfs.c
>+++ b/drivers/pci/pci-sysfs.c
>@@ -1217,11 +1217,9 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
> 		return -EINVAL;
>
> 	if (!pci_mmap_fits(pdev, bar, vma, PCI_MMAP_SYSFS)) {
>-		WARN(1, "process \"%s\" tried to map 0x%08lx bytes at page 0x%08lx on %s BAR %d (start 0x%16Lx, size 0x%16Lx)\n",
>+		dev_info(&pdev->dev, "process \"%s\" tried to map 0x%lx bytes at page 0x%lx of BAR %d %pR\n",
> 			current->comm, vma->vm_end-vma->vm_start, vma->vm_pgoff,
>-			pci_name(pdev), bar,
>-			(u64)pci_resource_start(pdev, bar),
>-			(u64)pci_resource_len(pdev, bar));
>+			bar, res);
> 		return -EINVAL;
> 	}
> 	mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io;
>