* Re: [PATCHv2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr
2018-12-14 4:07 [PATCHv2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr Pingfan Liu
@ 2018-12-21 7:18 ` Baoquan He
2018-12-21 7:27 ` Baoquan He
2018-12-26 1:47 ` Dave Young
2018-12-26 1:57 ` Dave Young
2 siblings, 1 reply; 7+ messages in thread
From: Baoquan He @ 2018-12-21 7:18 UTC (permalink / raw)
To: Pingfan Liu, Andrew Morton
Cc: linux-kernel, Dave Young, yinghai, vgoyal, kexec
On 12/14/18 at 12:07pm, Pingfan Liu wrote:
> Customer reported a bug on a high end server with many pcie devices, where
> kernel bootup with crashkernel=384M, and kaslr is enabled. Even
> though we still see much memory under 896 MB, the finding still failed
> intermittently. Because currently we can only find region under 896 MB,
> if w/0 ',high' specified. Then KASLR breaks 896 MB into several parts
> randomly, and crashkernel reservation need be aligned to 128 MB, that's
> why failure is found. It raises confusion to the end user that sometimes
> crashkernel=X works while sometimes fails.
> If want to make it succeed, customer can change kernel option to
> "crashkernel=384M, high". Just this give "crashkernel=xx@yy" a very
> limited space to behave even though its grammer looks more generic.
> And we can't answer questions raised from customer that confidently:
> 1) why it doesn't succeed to reserve 896 MB;
> 2) what's wrong with memory region under 4G;
> 3) why I have to add ',high', I only require 384 MB, not 3840 MB.
>
> This patch simplifies the method suggested in the mail [1]. It just goes
> bottom-up to find a candidate region for crashkernel. The bottom-up may be
> better compatible with the old reservation style, i.e. still want to get
> memory region from 896 MB firstly, then [896 MB, 4G], finally above 4G.
>
> There is one trivial thing about the compatibility with old kexec-tools:
> if the reserved region is above 896M, then old tool will fail to load
> bzImage. But without this patch, the old tool also fail since there is no
> memory below 896M can be reserved for crashkernel.
>
> [1]: http://lists.infradead.org/pipermail/kexec/2017-October/019571.html
> Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Baoquan He <bhe@redhat.com>
> Cc: yinghai@kernel.org,
> Cc: vgoyal@redhat.com
> Cc: kexec@lists.infradead.org
>
> ---
> v1->v2:
> improve commit log
> arch/x86/kernel/setup.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
This is a bug fix and urged by our customer.
I personally think crashkernel=xx@ is a generic synctax, the current
code making it search only under 896 MB seems not so reasonable.
Ack this patch.
Acked-by: Baoquan He <bhe@redhat.com>
Thanks
Baoquan
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index d494b9b..60f12c4 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -541,15 +541,18 @@ static void __init reserve_crashkernel(void)
>
> /* 0 means: find the address automatically */
> if (crash_base <= 0) {
> + if (!memblock_bottom_up())
> + memblock_set_bottom_up(true);
> /*
> * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> * as old kexec-tools loads bzImage below that, unless
> * "crashkernel=size[KMG],high" is specified.
> */
> crash_base = memblock_find_in_range(CRASH_ALIGN,
> - high ? CRASH_ADDR_HIGH_MAX
> - : CRASH_ADDR_LOW_MAX,
> - crash_size, CRASH_ALIGN);
> + (max_pfn * PAGE_SIZE), crash_size, CRASH_ALIGN);
> + if (!memblock_bottom_up())
> + memblock_set_bottom_up(false);
> +
> if (!crash_base) {
> pr_info("crashkernel reservation failed - No suitable area found.\n");
> return;
> --
> 2.7.4
>
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCHv2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr
2018-12-21 7:18 ` Baoquan He
@ 2018-12-21 7:27 ` Baoquan He
0 siblings, 0 replies; 7+ messages in thread
From: Baoquan He @ 2018-12-21 7:27 UTC (permalink / raw)
To: Pingfan Liu, Andrew Morton
Cc: linux-kernel, Dave Young, yinghai, vgoyal, kexec
On 12/21/18 at 03:18pm, Baoquan He wrote:
> On 12/14/18 at 12:07pm, Pingfan Liu wrote:
> > Customer reported a bug on a high end server with many pcie devices, where
> > kernel bootup with crashkernel=384M, and kaslr is enabled. Even
> > though we still see much memory under 896 MB, the finding still failed
> > intermittently. Because currently we can only find region under 896 MB,
> > if w/0 ',high' specified. Then KASLR breaks 896 MB into several parts
> > randomly, and crashkernel reservation need be aligned to 128 MB, that's
> > why failure is found. It raises confusion to the end user that sometimes
> > crashkernel=X works while sometimes fails.
> > If want to make it succeed, customer can change kernel option to
> > "crashkernel=384M, high". Just this give "crashkernel=xx@yy" a very
> > limited space to behave even though its grammer looks more generic.
> > And we can't answer questions raised from customer that confidently:
> > 1) why it doesn't succeed to reserve 896 MB;
> > 2) what's wrong with memory region under 4G;
> > 3) why I have to add ',high', I only require 384 MB, not 3840 MB.
> >
> > This patch simplifies the method suggested in the mail [1]. It just goes
> > bottom-up to find a candidate region for crashkernel. The bottom-up may be
> > better compatible with the old reservation style, i.e. still want to get
> > memory region from 896 MB firstly, then [896 MB, 4G], finally above 4G.
> >
> > There is one trivial thing about the compatibility with old kexec-tools:
> > if the reserved region is above 896M, then old tool will fail to load
> > bzImage. But without this patch, the old tool also fail since there is no
> > memory below 896M can be reserved for crashkernel.
> >
> > [1]: http://lists.infradead.org/pipermail/kexec/2017-October/019571.html
> > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> > Cc: Dave Young <dyoung@redhat.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Baoquan He <bhe@redhat.com>
> > Cc: yinghai@kernel.org,
> > Cc: vgoyal@redhat.com
> > Cc: kexec@lists.infradead.org
> >
> > ---
> > v1->v2:
> > improve commit log
> > arch/x86/kernel/setup.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
>
> This is a bug fix and urged by our customer.
>
> I personally think crashkernel=xx@ is a generic synctax, the current
~~ s/@/M
> code making it search only under 896 MB seems not so reasonable.
>
> Ack this patch.
>
> Acked-by: Baoquan He <bhe@redhat.com>
>
> Thanks
> Baoquan
>
> >
> > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> > index d494b9b..60f12c4 100644
> > --- a/arch/x86/kernel/setup.c
> > +++ b/arch/x86/kernel/setup.c
> > @@ -541,15 +541,18 @@ static void __init reserve_crashkernel(void)
> >
> > /* 0 means: find the address automatically */
> > if (crash_base <= 0) {
> > + if (!memblock_bottom_up())
> > + memblock_set_bottom_up(true);
> > /*
> > * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> > * as old kexec-tools loads bzImage below that, unless
> > * "crashkernel=size[KMG],high" is specified.
> > */
> > crash_base = memblock_find_in_range(CRASH_ALIGN,
> > - high ? CRASH_ADDR_HIGH_MAX
> > - : CRASH_ADDR_LOW_MAX,
> > - crash_size, CRASH_ALIGN);
> > + (max_pfn * PAGE_SIZE), crash_size, CRASH_ALIGN);
> > + if (!memblock_bottom_up())
> > + memblock_set_bottom_up(false);
> > +
> > if (!crash_base) {
> > pr_info("crashkernel reservation failed - No suitable area found.\n");
> > return;
> > --
> > 2.7.4
> >
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCHv2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr
2018-12-14 4:07 [PATCHv2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr Pingfan Liu
2018-12-21 7:18 ` Baoquan He
@ 2018-12-26 1:47 ` Dave Young
2018-12-27 2:57 ` Pingfan Liu
2018-12-26 1:57 ` Dave Young
2 siblings, 1 reply; 7+ messages in thread
From: Dave Young @ 2018-12-26 1:47 UTC (permalink / raw)
To: Pingfan Liu
Cc: linux-kernel, Baoquan He, kexec, Andrew Morton, yinghai, vgoyal
On 12/14/18 at 12:07pm, Pingfan Liu wrote:
> Customer reported a bug on a high end server with many pcie devices, where
> kernel bootup with crashkernel=384M, and kaslr is enabled. Even
> though we still see much memory under 896 MB, the finding still failed
> intermittently. Because currently we can only find region under 896 MB,
> if w/0 ',high' specified. Then KASLR breaks 896 MB into several parts
> randomly, and crashkernel reservation need be aligned to 128 MB, that's
> why failure is found. It raises confusion to the end user that sometimes
> crashkernel=X works while sometimes fails.
> If want to make it succeed, customer can change kernel option to
> "crashkernel=384M, high". Just this give "crashkernel=xx@yy" a very
> limited space to behave even though its grammer looks more generic.
> And we can't answer questions raised from customer that confidently:
> 1) why it doesn't succeed to reserve 896 MB;
> 2) what's wrong with memory region under 4G;
> 3) why I have to add ',high', I only require 384 MB, not 3840 MB.
>
> This patch simplifies the method suggested in the mail [1]. It just goes
> bottom-up to find a candidate region for crashkernel. The bottom-up may be
> better compatible with the old reservation style, i.e. still want to get
> memory region from 896 MB firstly, then [896 MB, 4G], finally above 4G.
>
> There is one trivial thing about the compatibility with old kexec-tools:
> if the reserved region is above 896M, then old tool will fail to load
> bzImage. But without this patch, the old tool also fail since there is no
> memory below 896M can be reserved for crashkernel.
>
> [1]: http://lists.infradead.org/pipermail/kexec/2017-October/019571.html
> Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Baoquan He <bhe@redhat.com>
> Cc: yinghai@kernel.org,
> Cc: vgoyal@redhat.com
> Cc: kexec@lists.infradead.org
>
> ---
> v1->v2:
> improve commit log
> arch/x86/kernel/setup.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index d494b9b..60f12c4 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -541,15 +541,18 @@ static void __init reserve_crashkernel(void)
>
> /* 0 means: find the address automatically */
> if (crash_base <= 0) {
> + if (!memblock_bottom_up())
> + memblock_set_bottom_up(true);
> /*
> * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> * as old kexec-tools loads bzImage below that, unless
> * "crashkernel=size[KMG],high" is specified.
> */
> crash_base = memblock_find_in_range(CRASH_ALIGN,
> - high ? CRASH_ADDR_HIGH_MAX
> - : CRASH_ADDR_LOW_MAX,
> - crash_size, CRASH_ALIGN);
> + (max_pfn * PAGE_SIZE), crash_size, CRASH_ALIGN);
> + if (!memblock_bottom_up())
> + memblock_set_bottom_up(false);
The previous memblock_set_bottom_up(true) set it as true, so
"!memblock_bottom_up()" is impossible, not sure what is the point of
this condition check.
Do you want to restore the original memblock direction? If so a variable
to save the old direction is needed. But is this really necessary?
Do you know any side effects of setting the bottom up as true?
> +
> if (!crash_base) {
> pr_info("crashkernel reservation failed - No suitable area found.\n");
> return;
> --
> 2.7.4
>
>
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
Thanks
Dave
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCHv2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr
2018-12-26 1:47 ` Dave Young
@ 2018-12-27 2:57 ` Pingfan Liu
0 siblings, 0 replies; 7+ messages in thread
From: Pingfan Liu @ 2018-12-27 2:57 UTC (permalink / raw)
To: Dave Young
Cc: linux-kernel, Baoquan He, kexec, Andrew Morton, yinghai, vgoyal
On Wed, Dec 26, 2018 at 9:47 AM Dave Young <dyoung@redhat.com> wrote:
>
> On 12/14/18 at 12:07pm, Pingfan Liu wrote:
> > Customer reported a bug on a high end server with many pcie devices, where
> > kernel bootup with crashkernel=384M, and kaslr is enabled. Even
> > though we still see much memory under 896 MB, the finding still failed
> > intermittently. Because currently we can only find region under 896 MB,
> > if w/0 ',high' specified. Then KASLR breaks 896 MB into several parts
> > randomly, and crashkernel reservation need be aligned to 128 MB, that's
> > why failure is found. It raises confusion to the end user that sometimes
> > crashkernel=X works while sometimes fails.
> > If want to make it succeed, customer can change kernel option to
> > "crashkernel=384M, high". Just this give "crashkernel=xx@yy" a very
> > limited space to behave even though its grammer looks more generic.
> > And we can't answer questions raised from customer that confidently:
> > 1) why it doesn't succeed to reserve 896 MB;
> > 2) what's wrong with memory region under 4G;
> > 3) why I have to add ',high', I only require 384 MB, not 3840 MB.
> >
> > This patch simplifies the method suggested in the mail [1]. It just goes
> > bottom-up to find a candidate region for crashkernel. The bottom-up may be
> > better compatible with the old reservation style, i.e. still want to get
> > memory region from 896 MB firstly, then [896 MB, 4G], finally above 4G.
> >
> > There is one trivial thing about the compatibility with old kexec-tools:
> > if the reserved region is above 896M, then old tool will fail to load
> > bzImage. But without this patch, the old tool also fail since there is no
> > memory below 896M can be reserved for crashkernel.
> >
> > [1]: http://lists.infradead.org/pipermail/kexec/2017-October/019571.html
> > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> > Cc: Dave Young <dyoung@redhat.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Baoquan He <bhe@redhat.com>
> > Cc: yinghai@kernel.org,
> > Cc: vgoyal@redhat.com
> > Cc: kexec@lists.infradead.org
> >
> > ---
> > v1->v2:
> > improve commit log
> > arch/x86/kernel/setup.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> > index d494b9b..60f12c4 100644
> > --- a/arch/x86/kernel/setup.c
> > +++ b/arch/x86/kernel/setup.c
> > @@ -541,15 +541,18 @@ static void __init reserve_crashkernel(void)
> >
> > /* 0 means: find the address automatically */
> > if (crash_base <= 0) {
> > + if (!memblock_bottom_up())
> > + memblock_set_bottom_up(true);
> > /*
> > * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> > * as old kexec-tools loads bzImage below that, unless
> > * "crashkernel=size[KMG],high" is specified.
> > */
> > crash_base = memblock_find_in_range(CRASH_ALIGN,
> > - high ? CRASH_ADDR_HIGH_MAX
> > - : CRASH_ADDR_LOW_MAX,
> > - crash_size, CRASH_ALIGN);
> > + (max_pfn * PAGE_SIZE), crash_size, CRASH_ALIGN);
> > + if (!memblock_bottom_up())
> > + memblock_set_bottom_up(false);
>
> The previous memblock_set_bottom_up(true) set it as true, so
> "!memblock_bottom_up()" is impossible, not sure what is the point of
> this condition check.
>
> Do you want to restore the original memblock direction? If so a variable
> to save the old direction is needed. But is this really necessary?
> Do you know any side effects of setting the bottom up as true?
>
Yes, will fix it.
Thanks
> > +
> > if (!crash_base) {
> > pr_info("crashkernel reservation failed - No suitable area found.\n");
> > return;
> > --
> > 2.7.4
> >
> >
> > _______________________________________________
> > kexec mailing list
> > kexec@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/kexec
>
> Thanks
> Dave
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCHv2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr
2018-12-14 4:07 [PATCHv2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr Pingfan Liu
2018-12-21 7:18 ` Baoquan He
2018-12-26 1:47 ` Dave Young
@ 2018-12-26 1:57 ` Dave Young
2018-12-27 2:55 ` Pingfan Liu
2 siblings, 1 reply; 7+ messages in thread
From: Dave Young @ 2018-12-26 1:57 UTC (permalink / raw)
To: Pingfan Liu
Cc: linux-kernel, Andrew Morton, Baoquan He, yinghai, vgoyal, kexec
On 12/14/18 at 12:07pm, Pingfan Liu wrote:
> Customer reported a bug on a high end server with many pcie devices, where
> kernel bootup with crashkernel=384M, and kaslr is enabled. Even
> though we still see much memory under 896 MB, the finding still failed
> intermittently. Because currently we can only find region under 896 MB,
> if w/0 ',high' specified. Then KASLR breaks 896 MB into several parts
> randomly, and crashkernel reservation need be aligned to 128 MB, that's
> why failure is found. It raises confusion to the end user that sometimes
> crashkernel=X works while sometimes fails.
> If want to make it succeed, customer can change kernel option to
> "crashkernel=384M, high". Just this give "crashkernel=xx@yy" a very
> limited space to behave even though its grammer looks more generic.
> And we can't answer questions raised from customer that confidently:
> 1) why it doesn't succeed to reserve 896 MB;
> 2) what's wrong with memory region under 4G;
> 3) why I have to add ',high', I only require 384 MB, not 3840 MB.
>
> This patch simplifies the method suggested in the mail [1]. It just goes
> bottom-up to find a candidate region for crashkernel. The bottom-up may be
> better compatible with the old reservation style, i.e. still want to get
> memory region from 896 MB firstly, then [896 MB, 4G], finally above 4G.
>
> There is one trivial thing about the compatibility with old kexec-tools:
> if the reserved region is above 896M, then old tool will fail to load
> bzImage. But without this patch, the old tool also fail since there is no
> memory below 896M can be reserved for crashkernel.
>
> [1]: http://lists.infradead.org/pipermail/kexec/2017-October/019571.html
> Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Baoquan He <bhe@redhat.com>
> Cc: yinghai@kernel.org,
> Cc: vgoyal@redhat.com
> Cc: kexec@lists.infradead.org
>
> ---
> v1->v2:
> improve commit log
> arch/x86/kernel/setup.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index d494b9b..60f12c4 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -541,15 +541,18 @@ static void __init reserve_crashkernel(void)
>
> /* 0 means: find the address automatically */
> if (crash_base <= 0) {
> + if (!memblock_bottom_up())
> + memblock_set_bottom_up(true);
Looking at the memblock_find_in_range_node code, it is allocating
bottom up in case bottom_up is true, but it will try to allocate above
kernel_end:
bottom_up_start = max(start, kernel_end);
If kernel lives very high eg. KASLR case, then this bottom up way does
not help. So probably previous old version to try 896M first then 4G
then maxmem is better.
> /*
> * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> * as old kexec-tools loads bzImage below that, unless
> * "crashkernel=size[KMG],high" is specified.
> */
> crash_base = memblock_find_in_range(CRASH_ALIGN,
> - high ? CRASH_ADDR_HIGH_MAX
> - : CRASH_ADDR_LOW_MAX,
> - crash_size, CRASH_ALIGN);
> + (max_pfn * PAGE_SIZE), crash_size, CRASH_ALIGN);
> + if (!memblock_bottom_up())
> + memblock_set_bottom_up(false);
> +
> if (!crash_base) {
> pr_info("crashkernel reservation failed - No suitable area found.\n");
> return;
> --
> 2.7.4
>
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCHv2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr
2018-12-26 1:57 ` Dave Young
@ 2018-12-27 2:55 ` Pingfan Liu
0 siblings, 0 replies; 7+ messages in thread
From: Pingfan Liu @ 2018-12-27 2:55 UTC (permalink / raw)
To: Dave Young
Cc: linux-kernel, Andrew Morton, Baoquan He, yinghai, vgoyal, kexec
On Wed, Dec 26, 2018 at 9:58 AM Dave Young <dyoung@redhat.com> wrote:
>
> On 12/14/18 at 12:07pm, Pingfan Liu wrote:
> > Customer reported a bug on a high end server with many pcie devices, where
> > kernel bootup with crashkernel=384M, and kaslr is enabled. Even
> > though we still see much memory under 896 MB, the finding still failed
> > intermittently. Because currently we can only find region under 896 MB,
> > if w/0 ',high' specified. Then KASLR breaks 896 MB into several parts
> > randomly, and crashkernel reservation need be aligned to 128 MB, that's
> > why failure is found. It raises confusion to the end user that sometimes
> > crashkernel=X works while sometimes fails.
> > If want to make it succeed, customer can change kernel option to
> > "crashkernel=384M, high". Just this give "crashkernel=xx@yy" a very
> > limited space to behave even though its grammer looks more generic.
> > And we can't answer questions raised from customer that confidently:
> > 1) why it doesn't succeed to reserve 896 MB;
> > 2) what's wrong with memory region under 4G;
> > 3) why I have to add ',high', I only require 384 MB, not 3840 MB.
> >
> > This patch simplifies the method suggested in the mail [1]. It just goes
> > bottom-up to find a candidate region for crashkernel. The bottom-up may be
> > better compatible with the old reservation style, i.e. still want to get
> > memory region from 896 MB firstly, then [896 MB, 4G], finally above 4G.
> >
> > There is one trivial thing about the compatibility with old kexec-tools:
> > if the reserved region is above 896M, then old tool will fail to load
> > bzImage. But without this patch, the old tool also fail since there is no
> > memory below 896M can be reserved for crashkernel.
> >
> > [1]: http://lists.infradead.org/pipermail/kexec/2017-October/019571.html
> > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> > Cc: Dave Young <dyoung@redhat.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Baoquan He <bhe@redhat.com>
> > Cc: yinghai@kernel.org,
> > Cc: vgoyal@redhat.com
> > Cc: kexec@lists.infradead.org
> >
> > ---
> > v1->v2:
> > improve commit log
> > arch/x86/kernel/setup.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> > index d494b9b..60f12c4 100644
> > --- a/arch/x86/kernel/setup.c
> > +++ b/arch/x86/kernel/setup.c
> > @@ -541,15 +541,18 @@ static void __init reserve_crashkernel(void)
> >
> > /* 0 means: find the address automatically */
> > if (crash_base <= 0) {
> > + if (!memblock_bottom_up())
> > + memblock_set_bottom_up(true);
>
> Looking at the memblock_find_in_range_node code, it is allocating
> bottom up in case bottom_up is true, but it will try to allocate above
> kernel_end:
>
> bottom_up_start = max(start, kernel_end);
>
> If kernel lives very high eg. KASLR case, then this bottom up way does
> not help. So probably previous old version to try 896M first then 4G
> then maxmem is better.
>
Yes, you are right. I will try to see whether it can be resolved or not.
Thanks,
Pingfan
> > /*
> > * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> > * as old kexec-tools loads bzImage below that, unless
> > * "crashkernel=size[KMG],high" is specified.
> > */
> > crash_base = memblock_find_in_range(CRASH_ALIGN,
> > - high ? CRASH_ADDR_HIGH_MAX
> > - : CRASH_ADDR_LOW_MAX,
> > - crash_size, CRASH_ALIGN);
> > + (max_pfn * PAGE_SIZE), crash_size, CRASH_ALIGN);
> > + if (!memblock_bottom_up())
> > + memblock_set_bottom_up(false);
> > +
> > if (!crash_base) {
> > pr_info("crashkernel reservation failed - No suitable area found.\n");
> > return;
> > --
> > 2.7.4
> >
^ permalink raw reply [flat|nested] 7+ messages in thread