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Message-ID: <CA+quRcbBCau+2h0fxncR3ck-PZeB2NzFJZxQVea3y0VHAHp2uQ@mail.gmail.com>
Date: Thu, 29 Nov 2012 21:15:44 +0800
From: andywu106建国 <wujianguo106@...il.com>
To: Wen Congyang <wency@...fujitsu.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
linux-acpi@...r.kernel.org, Len Brown <len.brown@...el.com>,
"Rafael J. Wysocki" <rjw@...k.pl>,
Andrew Morton <akpm@...ux-foundation.org>,
Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
Lai Jiangshan <laijs@...fujitsu.com>,
Jiang Liu <jiang.liu@...wei.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Minchan Kim <minchan.kim@...il.com>,
Mel Gorman <mgorman@...e.de>,
David Rientjes <rientjes@...gle.com>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
Toshi Kani <toshi.kani@...com>, Jiang Liu <liuj97@...il.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Christoph Lameter <cl@...ux.com>
Subject: Re: [Patch v5 5/7] acpi_memhotplug.c: don't allow to eject the memory
device if it is being used
2012/11/15 Wen Congyang <wency@...fujitsu.com>
>
> We eject the memory device even if it is in use. It is very dangerous,
> and it will cause the kernel to be panicked.
>
> CC: David Rientjes <rientjes@...gle.com>
> CC: Jiang Liu <liuj97@...il.com>
> CC: Len Brown <len.brown@...el.com>
> CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> CC: Paul Mackerras <paulus@...ba.org>
> CC: Christoph Lameter <cl@...ux.com>
> Cc: Minchan Kim <minchan.kim@...il.com>
> CC: Andrew Morton <akpm@...ux-foundation.org>
> CC: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> CC: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> CC: Rafael J. Wysocki <rjw@...k.pl>
> CC: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> Signed-off-by: Wen Congyang <wency@...fujitsu.com>
> ---
> drivers/acpi/acpi_memhotplug.c | 42 +++++++++++++++++++++++++++++++++---------
> 1 file changed, 33 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
> index e52ad5d..f7e3007 100644
> --- a/drivers/acpi/acpi_memhotplug.c
> +++ b/drivers/acpi/acpi_memhotplug.c
> @@ -78,6 +78,7 @@ struct acpi_memory_info {
> unsigned short caching; /* memory cache attribute */
> unsigned short write_protect; /* memory read/write attribute */
> unsigned int enabled:1;
> + unsigned int failed:1;
> };
>
> struct acpi_memory_device {
> @@ -257,9 +258,23 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
> node = memory_add_physaddr_to_nid(info->start_addr);
>
> result = add_memory(node, info->start_addr, info->length);
> - if (result)
> +
> + /*
> + * If the memory block has been used by the kernel, add_memory()
> + * returns -EEXIST. If add_memory() returns the other error, it
> + * means that this memory block is not used by the kernel.
> + */
> + if (result && result != -EEXIST) {
> + info->failed = 1;
> continue;
> - info->enabled = 1;
> + }
> +
> + if (!result)
> + info->enabled = 1;
Hi Congyang,
If a memory device booting with the system, the info->enable will equal to 0,
and can not be hot-removed in acpi_memory_remove_memory(), right?
Thanks,
Jianguo Wu
>
> + /*
> + * Add num_enable even if add_memory() returns -EEXIST, so the
> + * device is bound to this driver.
> + */
> num_enabled++;
> }
> if (!num_enabled) {
> @@ -280,21 +295,30 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
>
> static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
> {
> - int result;
> + int result = 0;
> struct acpi_memory_info *info, *n;
>
> list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
> - if (info->enabled) {
> - result = remove_memory(info->start_addr, info->length);
> - if (result)
> - return result;
> - }
> + if (info->failed)
> + /* The kernel does not use this memory block */
> + continue;
> +
> + if (!info->enabled)
> + /*
> + * The kernel uses this memory block, but it may be not
> + * managed by us.
> + */
> + return -EBUSY;
> +
> + result = remove_memory(info->start_addr, info->length);
> + if (result)
> + return result;
>
> list_del(&info->list);
> kfree(info);
> }
>
> - return 0;
> + return result;
> }
>
> static void acpi_memory_device_notify(acpi_handle handle, u32 event, void *data)
> --
> 1.8.0
>
> --
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