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Wed, 05 Jun 2019 14:21:07 -0700 (PDT) Date: Wed, 5 Jun 2019 21:21:06 +0000 From: Wei Yang To: David Hildenbrand Subject: Re: [PATCH v3 10/11] mm/memory_hotplug: Make unregister_memory_block_under_nodes() never fail Message-ID: <20190605212106.6folqx2zawbvzzmm@master> References: <20190527111152.16324-1-david@redhat.com> <20190527111152.16324-11-david@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190527111152.16324-11-david@redhat.com> User-Agent: NeoMutt/20170113 (1.7.2) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190605_142110_711660_C4178075 X-CRM114-Status: GOOD ( 15.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Wei Yang Cc: linux-s390@vger.kernel.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Greg Kroah-Hartman , Mark Brown , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, Wei Yang , linux-mm@kvack.org, "David S. Miller" , Jonathan Cameron , Alex Deucher , Igor Mammedov , akpm@linux-foundation.org, Chris Wilson , linuxppc-dev@lists.ozlabs.org, Dan Williams , linux-arm-kernel@lists.infradead.org, Oscar Salvador Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, May 27, 2019 at 01:11:51PM +0200, David Hildenbrand wrote: >We really don't want anything during memory hotunplug to fail. >We always pass a valid memory block device, that check can go. Avoid >allocating memory and eventually failing. As we are always called under >lock, we can use a static piece of memory. This avoids having to put >the structure onto the stack, having to guess about the stack size >of callers. > >Patch inspired by a patch from Oscar Salvador. > >In the future, there might be no need to iterate over nodes at all. >mem->nid should tell us exactly what to remove. Memory block devices >with mixed nodes (added during boot) should properly fenced off and never >removed. > >Cc: Greg Kroah-Hartman >Cc: "Rafael J. Wysocki" >Cc: Alex Deucher >Cc: "David S. Miller" >Cc: Mark Brown >Cc: Chris Wilson >Cc: David Hildenbrand >Cc: Oscar Salvador >Cc: Andrew Morton >Cc: Jonathan Cameron >Signed-off-by: David Hildenbrand Reviewed-by: Wei Yang >--- > drivers/base/node.c | 18 +++++------------- > include/linux/node.h | 5 ++--- > 2 files changed, 7 insertions(+), 16 deletions(-) > >diff --git a/drivers/base/node.c b/drivers/base/node.c >index 04fdfa99b8bc..9be88fd05147 100644 >--- a/drivers/base/node.c >+++ b/drivers/base/node.c >@@ -803,20 +803,14 @@ int register_mem_sect_under_node(struct memory_block *mem_blk, void *arg) > > /* > * Unregister memory block device under all nodes that it spans. >+ * Has to be called with mem_sysfs_mutex held (due to unlinked_nodes). > */ >-int unregister_memory_block_under_nodes(struct memory_block *mem_blk) >+void unregister_memory_block_under_nodes(struct memory_block *mem_blk) > { >- NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL); > unsigned long pfn, sect_start_pfn, sect_end_pfn; >+ static nodemask_t unlinked_nodes; > >- if (!mem_blk) { >- NODEMASK_FREE(unlinked_nodes); >- return -EFAULT; >- } >- if (!unlinked_nodes) >- return -ENOMEM; >- nodes_clear(*unlinked_nodes); >- >+ nodes_clear(unlinked_nodes); > sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr); > sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr); > for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) { >@@ -827,15 +821,13 @@ int unregister_memory_block_under_nodes(struct memory_block *mem_blk) > continue; > if (!node_online(nid)) > continue; >- if (node_test_and_set(nid, *unlinked_nodes)) >+ if (node_test_and_set(nid, unlinked_nodes)) > continue; > sysfs_remove_link(&node_devices[nid]->dev.kobj, > kobject_name(&mem_blk->dev.kobj)); > sysfs_remove_link(&mem_blk->dev.kobj, > kobject_name(&node_devices[nid]->dev.kobj)); > } >- NODEMASK_FREE(unlinked_nodes); >- return 0; > } > > int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn) >diff --git a/include/linux/node.h b/include/linux/node.h >index 02a29e71b175..548c226966a2 100644 >--- a/include/linux/node.h >+++ b/include/linux/node.h >@@ -139,7 +139,7 @@ extern int register_cpu_under_node(unsigned int cpu, unsigned int nid); > extern int unregister_cpu_under_node(unsigned int cpu, unsigned int nid); > extern int register_mem_sect_under_node(struct memory_block *mem_blk, > void *arg); >-extern int unregister_memory_block_under_nodes(struct memory_block *mem_blk); >+extern void unregister_memory_block_under_nodes(struct memory_block *mem_blk); > > extern int register_memory_node_under_compute_node(unsigned int mem_nid, > unsigned int cpu_nid, >@@ -175,9 +175,8 @@ static inline int register_mem_sect_under_node(struct memory_block *mem_blk, > { > return 0; > } >-static inline int unregister_memory_block_under_nodes(struct memory_block *mem_blk) >+static inline void unregister_memory_block_under_nodes(struct memory_block *mem_blk) > { >- return 0; > } > > static inline void register_hugetlbfs_with_node(node_registration_func_t reg, >-- >2.20.1 -- Wei Yang Help you, Help me _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel