From mboxrd@z Thu Jan 1 00:00:00 1970 From: Baoquan He Date: Wed, 11 May 2022 18:06:23 +0800 Subject: [PATCH] arm64: kdump: Do not allocate crash low memory if not needed In-Reply-To: <8922e61e-ab7c-6e48-ad8c-57b75156a0f2@huawei.com> References: <20220511032033.426-1-thunder.leizhen@huawei.com> <8922e61e-ab7c-6e48-ad8c-57b75156a0f2@huawei.com> Message-ID: <20220511100623.GF122876@MiWiFi-R3L-srv> 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 05:50pm, Leizhen (ThunderTown) wrote: > > > On 2022/5/11 17:06, Baoquan He wrote: > > 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 > > This is Catalin's response a few days ago: > Slightly more correct is "This one lets the user specify..." > > I didn't googled "This one lets", but I googled "It lets". I think he wrote it right. > > Both "the user" and "users" seem to be right. Yeah, I forgot the 'this one lets' part, and I am fine too with the 'the use'if it's right. So please ignore the comment. > > > > > > 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 > >> > > > > . > > > > -- > Regards, > Zhen Lei >