From mboxrd@z Thu Jan 1 00:00:00 1970 From: Baoquan He Date: Wed, 11 May 2022 17:06:51 +0800 Subject: [PATCH] arm64: kdump: Do not allocate crash low memory if not needed In-Reply-To: <20220511032033.426-1-thunder.leizhen@huawei.com> References: <20220511032033.426-1-thunder.leizhen@huawei.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kexec@lists.infradead.org On 05/11/22 at 11:20am, Zhen Lei wrote: > When "crashkernel=X,high" is specified, the specified "crashkernel=Y,low" > memory is not required in the following corner cases: > 1. If both CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, it means > that the devices can access any memory. > 2. If the system memory is small, the crash high memory may be allocated > from the DMA zones. If that happens, there's no need to allocate > another crash low memory because there's already one. > > Add condition '(crash_base >= CRASH_ADDR_LOW_MAX)' to determine whether > the 'high' memory is allocated above DMA zones. Note: when both > CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, the entire physical > memory is DMA accessible, CRASH_ADDR_LOW_MAX equals 'PHYS_MASK + 1'. > > Signed-off-by: Zhen Lei > --- > Documentation/admin-guide/kernel-parameters.txt | 5 +++-- > arch/arm64/mm/init.c | 3 ++- > 2 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index f6ff55840751a78..1b543c3109f4851 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -823,7 +823,7 @@ > low memory is needed to make sure DMA buffers for 32-bit > devices won't run out. Kernel would try to allocate > at least 256M below 4G automatically. > - This one let user to specify own low range under 4G > + This one lets the user specify own low range under 4G ~ This one let users specify own low range ... Other than this nitpick, LGTM Acked-by: Baoquan He > for second kernel instead. > 0: to disable low allocation. > It will be ignored when crashkernel=X,high is not used > @@ -832,7 +832,8 @@ > [KNL, ARM64] range in low memory. > This one lets the user specify a low range in the > DMA zone for the crash dump kernel. > - It will be ignored when crashkernel=X,high is not used. > + It will be ignored when crashkernel=X,high is not used > + or memory reserved is located in the DMA zones. > > cryptomgr.notests > [KNL] Disable crypto self-tests > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 18ba66c90991ea0..ac510fb6a2c0189 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -170,7 +170,8 @@ static void __init reserve_crashkernel(void) > return; > } > > - if (crash_low_size && reserve_crashkernel_low(crash_low_size)) { > + if ((crash_base >= CRASH_ADDR_LOW_MAX) && > + crash_low_size && reserve_crashkernel_low(crash_low_size)) { > memblock_phys_free(crash_base, crash_size); > return; > } > -- > 2.25.1 >