From: Gerald Schaefer <gerald.schaefer@linux.ibm.com> To: Mike Rapoport <rppt@kernel.org> Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, Catalin Marinas <catalin.marinas@arm.com>, Christian Borntraeger <borntraeger@de.ibm.com>, David Hildenbrand <david@redhat.com>, Heiko Carstens <hca@linux.ibm.com>, Mike Rapoport <rppt@linux.ibm.com>, Russell King <linux@armlinux.org.uk>, Thomas Bogendoerfer <tsbogend@alpha.franken.de>, Vasily Gorbik <gor@linux.ibm.com>, Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org Subject: Re: [RFC/RFT PATCH 1/5] s390: make crashk_res resource a child of "System RAM" Date: Tue, 1 Jun 2021 15:18:36 +0200 [thread overview] Message-ID: <20210601151836.1f3a90e0@thinkpad> (raw) In-Reply-To: <20210531122959.23499-2-rppt@kernel.org> On Mon, 31 May 2021 15:29:55 +0300 Mike Rapoport <rppt@kernel.org> wrote: > From: Mike Rapoport <rppt@linux.ibm.com> > > Commit 4e042af463f8 ("s390/kexec: fix crash on resize of reserved memory") > added a comment that says "crash kernel resource should not be part of the > System RAM resource" but never explained why. As it looks from the code in > the kernel and in kexec there is no actual reason for that. Still testing, but so far everything works fine. > > Keeping crashk_res inline with other resources makes code simpler and > cleaner, and allows future consolidation of the resources setup across > several architectures. > > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> > --- > arch/s390/kernel/setup.c | 21 +++++---------------- > 1 file changed, 5 insertions(+), 16 deletions(-) > > diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c > index 5aab59ad5688..30430e7c1b03 100644 > --- a/arch/s390/kernel/setup.c > +++ b/arch/s390/kernel/setup.c > @@ -500,6 +500,9 @@ static struct resource __initdata *standard_resources[] = { > &code_resource, > &data_resource, > &bss_resource, > +#ifdef CONFIG_CRASH_DUMP > + &crashk_res, > +#endif > }; > > static void __init setup_resources(void) > @@ -535,7 +538,7 @@ static void __init setup_resources(void) > > for (j = 0; j < ARRAY_SIZE(standard_resources); j++) { > std_res = standard_resources[j]; > - if (std_res->start < res->start || > + if (!std_res->end || std_res->start < res->start || > std_res->start > res->end) > continue; > if (std_res->end > res->end) { Why is this extra check for !std_res->end added here? I assume it might be needed later, after you moved this to common code, but I cannot see how any of the other patches in this series would require that. > @@ -552,20 +555,6 @@ static void __init setup_resources(void) > } > } > } > -#ifdef CONFIG_CRASH_DUMP > - /* > - * Re-add removed crash kernel memory as reserved memory. This makes > - * sure it will be mapped with the identity mapping and struct pages > - * will be created, so it can be resized later on. > - * However add it later since the crash kernel resource should not be > - * part of the System RAM resource. > - */ > - if (crashk_res.end) { > - memblock_add_node(crashk_res.start, resource_size(&crashk_res), 0); > - memblock_reserve(crashk_res.start, resource_size(&crashk_res)); > - insert_resource(&iomem_resource, &crashk_res); > - } > -#endif > } > > static void __init setup_ident_map_size(void) > @@ -733,7 +722,7 @@ static void __init reserve_crashkernel(void) > diag10_range(PFN_DOWN(crash_base), PFN_DOWN(crash_size)); > crashk_res.start = crash_base; > crashk_res.end = crash_base + crash_size - 1; > - memblock_remove(crash_base, crash_size); > + memblock_reserve(crash_base, crash_size); > pr_info("Reserving %lluMB of memory at %lluMB " > "for crashkernel (System RAM: %luMB)\n", > crash_size >> 20, crash_base >> 20, Other architectures check the return value of memblock_reserve() at this point, and exit crashkernel reservation if it fails. IIUC, the only reason why memblock_reserve() could fail would be the same reason why also memblock_remove() could fail, i.e. that memblock_double_array() would fail. And since we also do not check that at the moment, your patch would probably not (additionally) break anything. Still, this might be something for an add-on patch (for us). Do you happen to know how likely it would be that memblock_remove/reserve() could fail at this point?
WARNING: multiple messages have this Message-ID (diff)
From: Gerald Schaefer <gerald.schaefer@linux.ibm.com> To: Mike Rapoport <rppt@kernel.org> Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, Catalin Marinas <catalin.marinas@arm.com>, Christian Borntraeger <borntraeger@de.ibm.com>, David Hildenbrand <david@redhat.com>, Heiko Carstens <hca@linux.ibm.com>, Mike Rapoport <rppt@linux.ibm.com>, Russell King <linux@armlinux.org.uk>, Thomas Bogendoerfer <tsbogend@alpha.franken.de>, Vasily Gorbik <gor@linux.ibm.com>, Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org Subject: Re: [RFC/RFT PATCH 1/5] s390: make crashk_res resource a child of "System RAM" Date: Tue, 1 Jun 2021 15:18:36 +0200 [thread overview] Message-ID: <20210601151836.1f3a90e0@thinkpad> (raw) In-Reply-To: <20210531122959.23499-2-rppt@kernel.org> On Mon, 31 May 2021 15:29:55 +0300 Mike Rapoport <rppt@kernel.org> wrote: > From: Mike Rapoport <rppt@linux.ibm.com> > > Commit 4e042af463f8 ("s390/kexec: fix crash on resize of reserved memory") > added a comment that says "crash kernel resource should not be part of the > System RAM resource" but never explained why. As it looks from the code in > the kernel and in kexec there is no actual reason for that. Still testing, but so far everything works fine. > > Keeping crashk_res inline with other resources makes code simpler and > cleaner, and allows future consolidation of the resources setup across > several architectures. > > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> > --- > arch/s390/kernel/setup.c | 21 +++++---------------- > 1 file changed, 5 insertions(+), 16 deletions(-) > > diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c > index 5aab59ad5688..30430e7c1b03 100644 > --- a/arch/s390/kernel/setup.c > +++ b/arch/s390/kernel/setup.c > @@ -500,6 +500,9 @@ static struct resource __initdata *standard_resources[] = { > &code_resource, > &data_resource, > &bss_resource, > +#ifdef CONFIG_CRASH_DUMP > + &crashk_res, > +#endif > }; > > static void __init setup_resources(void) > @@ -535,7 +538,7 @@ static void __init setup_resources(void) > > for (j = 0; j < ARRAY_SIZE(standard_resources); j++) { > std_res = standard_resources[j]; > - if (std_res->start < res->start || > + if (!std_res->end || std_res->start < res->start || > std_res->start > res->end) > continue; > if (std_res->end > res->end) { Why is this extra check for !std_res->end added here? I assume it might be needed later, after you moved this to common code, but I cannot see how any of the other patches in this series would require that. > @@ -552,20 +555,6 @@ static void __init setup_resources(void) > } > } > } > -#ifdef CONFIG_CRASH_DUMP > - /* > - * Re-add removed crash kernel memory as reserved memory. This makes > - * sure it will be mapped with the identity mapping and struct pages > - * will be created, so it can be resized later on. > - * However add it later since the crash kernel resource should not be > - * part of the System RAM resource. > - */ > - if (crashk_res.end) { > - memblock_add_node(crashk_res.start, resource_size(&crashk_res), 0); > - memblock_reserve(crashk_res.start, resource_size(&crashk_res)); > - insert_resource(&iomem_resource, &crashk_res); > - } > -#endif > } > > static void __init setup_ident_map_size(void) > @@ -733,7 +722,7 @@ static void __init reserve_crashkernel(void) > diag10_range(PFN_DOWN(crash_base), PFN_DOWN(crash_size)); > crashk_res.start = crash_base; > crashk_res.end = crash_base + crash_size - 1; > - memblock_remove(crash_base, crash_size); > + memblock_reserve(crash_base, crash_size); > pr_info("Reserving %lluMB of memory at %lluMB " > "for crashkernel (System RAM: %luMB)\n", > crash_size >> 20, crash_base >> 20, Other architectures check the return value of memblock_reserve() at this point, and exit crashkernel reservation if it fails. IIUC, the only reason why memblock_reserve() could fail would be the same reason why also memblock_remove() could fail, i.e. that memblock_double_array() would fail. And since we also do not check that at the moment, your patch would probably not (additionally) break anything. Still, this might be something for an add-on patch (for us). Do you happen to know how likely it would be that memblock_remove/reserve() could fail at this point? _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-06-01 13:19 UTC|newest] Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-31 12:29 [RFC/RFT PATCH 0/5] consolidate "System RAM" resources setup Mike Rapoport 2021-05-31 12:29 ` Mike Rapoport 2021-05-31 12:29 ` [RFC/RFT PATCH 1/5] s390: make crashk_res resource a child of "System RAM" Mike Rapoport 2021-05-31 12:29 ` Mike Rapoport 2021-06-01 8:45 ` David Hildenbrand 2021-06-01 8:45 ` David Hildenbrand 2021-06-01 9:02 ` David Hildenbrand 2021-06-01 9:02 ` David Hildenbrand 2021-06-02 6:25 ` Mike Rapoport 2021-06-02 6:25 ` Mike Rapoport 2021-06-01 13:18 ` Gerald Schaefer [this message] 2021-06-01 13:18 ` Gerald Schaefer 2021-06-02 6:54 ` Mike Rapoport 2021-06-02 6:54 ` Mike Rapoport 2021-05-31 12:29 ` [RFC/RFT PATCH 2/5] memblock: introduce generic memblock_setup_resources() Mike Rapoport 2021-05-31 12:29 ` Mike Rapoport 2021-06-01 13:54 ` Russell King (Oracle) 2021-06-01 13:54 ` Russell King (Oracle) 2021-06-02 8:33 ` Mike Rapoport 2021-06-02 8:33 ` Mike Rapoport 2021-06-02 10:15 ` Russell King (Oracle) 2021-06-02 10:15 ` Russell King (Oracle) 2021-06-02 13:54 ` Mike Rapoport 2021-06-02 13:54 ` Mike Rapoport 2021-06-02 15:51 ` Russell King (Oracle) 2021-06-02 15:51 ` Russell King (Oracle) 2021-06-02 18:43 ` Mike Rapoport 2021-06-02 18:43 ` Mike Rapoport 2021-06-02 20:15 ` Russell King (Oracle) 2021-06-02 20:15 ` Russell King (Oracle) 2021-06-03 10:32 ` Mike Rapoport 2021-06-03 10:32 ` Mike Rapoport 2021-05-31 12:29 ` [RFC/RFT PATCH 3/5] arm: switch to " Mike Rapoport 2021-05-31 12:29 ` Mike Rapoport 2021-05-31 12:29 ` [RFC/RFT PATCH 4/5] MIPS: switch to generic memblock_setup_resources Mike Rapoport 2021-05-31 12:29 ` Mike Rapoport 2021-05-31 12:29 ` [RFC/RFT PATCH 5/5] arm64: switch to generic memblock_setup_resources() Mike Rapoport 2021-05-31 12:29 ` Mike Rapoport 2021-06-01 13:44 ` [RFC/RFT PATCH 0/5] consolidate "System RAM" resources setup Russell King (Oracle) 2021-06-01 13:44 ` Russell King (Oracle) 2021-06-02 7:05 ` Mike Rapoport 2021-06-02 7:05 ` Mike Rapoport
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