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Wed, 13 Mar 2019 07:03:09 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id 14G1ABeUVaYh; Wed, 13 Mar 2019 07:03:09 +0100 (CET) Received: from PO15451 (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id ABE178B75A; Wed, 13 Mar 2019 07:03:08 +0100 (CET) Subject: Re: [PATCH v2] powerpc/mm: move warning from resize_hpt_for_hotplug() To: Laurent Vivier , linux-kernel@vger.kernel.org References: <20190308105413.4302-1-lvivier@redhat.com> From: Christophe Leroy Message-ID: <3db6b64d-02d3-8aa7-80ca-3e469ea743ff@c-s.fr> Date: Wed, 13 Mar 2019 07:03:07 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.3 MIME-Version: 1.0 In-Reply-To: <20190308105413.4302-1-lvivier@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, David Gibson Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 08/03/2019 à 11:54, Laurent Vivier a écrit : > resize_hpt_for_hotplug() reports a warning when it cannot > resize the hash page table ("Unable to resize hash page > table to target order") but in some cases it's not a problem > and can make user thinks something has not worked properly. > > This patch moves the warning to arch_remove_memory() to > only report the problem when it is needed. > > Signed-off-by: Laurent Vivier > --- > arch/powerpc/include/asm/sparsemem.h | 4 ++-- > arch/powerpc/mm/hash_utils_64.c | 17 ++++++----------- > arch/powerpc/mm/mem.c | 3 ++- > arch/powerpc/platforms/pseries/lpar.c | 3 ++- > 4 files changed, 12 insertions(+), 15 deletions(-) > > diff --git a/arch/powerpc/include/asm/sparsemem.h b/arch/powerpc/include/asm/sparsemem.h > index 68da49320592..3192d454a733 100644 > --- a/arch/powerpc/include/asm/sparsemem.h > +++ b/arch/powerpc/include/asm/sparsemem.h > @@ -17,9 +17,9 @@ extern int create_section_mapping(unsigned long start, unsigned long end, int ni > extern int remove_section_mapping(unsigned long start, unsigned long end); > > #ifdef CONFIG_PPC_BOOK3S_64 > -extern void resize_hpt_for_hotplug(unsigned long new_mem_size); > +extern int resize_hpt_for_hotplug(unsigned long new_mem_size); > #else > -static inline void resize_hpt_for_hotplug(unsigned long new_mem_size) { } > +static inline int resize_hpt_for_hotplug(unsigned long new_mem_size) { return 0; } > #endif > > #ifdef CONFIG_NUMA > diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c > index 0cc7fbc3bd1c..40bb2a8326bb 100644 > --- a/arch/powerpc/mm/hash_utils_64.c > +++ b/arch/powerpc/mm/hash_utils_64.c > @@ -755,12 +755,12 @@ static unsigned long __init htab_get_table_size(void) > } > > #ifdef CONFIG_MEMORY_HOTPLUG > -void resize_hpt_for_hotplug(unsigned long new_mem_size) > +int resize_hpt_for_hotplug(unsigned long new_mem_size) > { > unsigned target_hpt_shift; > > if (!mmu_hash_ops.resize_hpt) > - return; > + return 0; > > target_hpt_shift = htab_shift_for_mem_size(new_mem_size); > > @@ -773,15 +773,10 @@ void resize_hpt_for_hotplug(unsigned long new_mem_size) > * current shift > */ > if ((target_hpt_shift > ppc64_pft_size) > - || (target_hpt_shift < (ppc64_pft_size - 1))) { > - int rc; > - > - rc = mmu_hash_ops.resize_hpt(target_hpt_shift); > - if (rc && (rc != -ENODEV)) > - printk(KERN_WARNING > - "Unable to resize hash page table to target order %d: %d\n", > - target_hpt_shift, rc); > - } > + || (target_hpt_shift < (ppc64_pft_size - 1))) The || should go on the line above and the two (target_hpt... should be aligned, and the () after the < are superflous. And indeed, we should (in another patch) rename 'target_hpt_shift' with a shorter name, this would avoid multiple lines. Ref https://www.kernel.org/doc/html/latest/process/coding-style.html#naming : LOCAL variable names should be short, and to the point. If you have some random integer loop counter, it should probably be called i. Calling it loop_counter is non-productive, if there is no chance of it being mis-understood. Similarly, tmp can be just about any type of variable that is used to hold a temporary value. If you are afraid to mix up your local variable names, you have another problem, which is called the function-growth-hormone-imbalance syndrome. See chapter 6 (Functions). Christophe > + return mmu_hash_ops.resize_hpt(target_hpt_shift); > + > + return 0; > } > > int hash__create_section_mapping(unsigned long start, unsigned long end, int nid) > diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c > index 33cc6f676fa6..0d40d970cf4a 100644 > --- a/arch/powerpc/mm/mem.c > +++ b/arch/powerpc/mm/mem.c > @@ -169,7 +169,8 @@ int __meminit arch_remove_memory(int nid, u64 start, u64 size, > */ > vm_unmap_aliases(); > > - resize_hpt_for_hotplug(memblock_phys_mem_size()); > + if (resize_hpt_for_hotplug(memblock_phys_mem_size()) == -ENOSPC) > + pr_warn("Hash collision while resizing HPT\n"); > > return ret; > } > diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c > index f2a9f0adc2d3..1034ef1fe2b4 100644 > --- a/arch/powerpc/platforms/pseries/lpar.c > +++ b/arch/powerpc/platforms/pseries/lpar.c > @@ -901,8 +901,10 @@ static int pseries_lpar_resize_hpt(unsigned long shift) > break; > > case H_PARAMETER: > + pr_warn("Invalid argument from H_RESIZE_HPT_PREPARE\n"); > return -EINVAL; > case H_RESOURCE: > + pr_warn("Operation not permitted from H_RESIZE_HPT_PREPARE\n"); > return -EPERM; > default: > pr_warn("Unexpected error %d from H_RESIZE_HPT_PREPARE\n", rc); > @@ -918,7 +920,6 @@ static int pseries_lpar_resize_hpt(unsigned long shift) > if (rc != 0) { > switch (state.commit_rc) { > case H_PTEG_FULL: > - pr_warn("Hash collision while resizing HPT\n"); > return -ENOSPC; > > default: >