From 639118d1571f70b1157b4bb5ac574b0ab0f38099 Mon Sep 17 00:00:00 2001 From: Kefeng Wang Date: Sat, 27 Aug 2022 19:20:43 +0800 Subject: mm: kill is_memblock_offlined() Directly check state of struct memory_block, no need a single function. Link: https://lkml.kernel.org/r/20220827112043.187028-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Reviewed-by: David Hildenbrand Reviewed-by: Oscar Salvador Reviewed-by: Anshuman Khandual Signed-off-by: Andrew Morton --- include/linux/memory_hotplug.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux/memory_hotplug.h') diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index e0b2209ab71c..54675791bc50 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -11,7 +11,6 @@ struct page; struct zone; struct pglist_data; struct mem_section; -struct memory_block; struct memory_group; struct resource; struct vmem_altmap; @@ -333,7 +332,6 @@ extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn, extern void remove_pfn_range_from_zone(struct zone *zone, unsigned long start_pfn, unsigned long nr_pages); -extern bool is_memblock_offlined(struct memory_block *mem); extern int sparse_add_section(int nid, unsigned long pfn, unsigned long nr_pages, struct vmem_altmap *altmap, struct dev_pagemap *pgmap); -- cgit v1.2.3 From b4a0215e11dcfe23a48c65c6d6c82c0c2c551a48 Mon Sep 17 00:00:00 2001 From: Kefeng Wang Date: Sat, 27 Aug 2022 19:19:59 +0800 Subject: mm: fix null-ptr-deref in kswapd_is_running() kswapd_run/stop() will set pgdat->kswapd to NULL, which could race with kswapd_is_running() in kcompactd(), kswapd_run/stop() kcompactd() kswapd_is_running() pgdat->kswapd // error or nomal ptr verify pgdat->kswapd // load non-NULL pgdat->kswapd pgdat->kswapd = NULL task_is_running(pgdat->kswapd) // Null pointer derefence KASAN reports the null-ptr-deref shown below, vmscan: Failed to start kswapd on node 0 ... BUG: KASAN: null-ptr-deref in kcompactd+0x440/0x504 Read of size 8 at addr 0000000000000024 by task kcompactd0/37 CPU: 0 PID: 37 Comm: kcompactd0 Kdump: loaded Tainted: G OE 5.10.60 #1 Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 Call trace: dump_backtrace+0x0/0x394 show_stack+0x34/0x4c dump_stack+0x158/0x1e4 __kasan_report+0x138/0x140 kasan_report+0x44/0xdc __asan_load8+0x94/0xd0 kcompactd+0x440/0x504 kthread+0x1a4/0x1f0 ret_from_fork+0x10/0x18 At present kswapd/kcompactd_run() and kswapd/kcompactd_stop() are protected by mem_hotplug_begin/done(), but without kcompactd(). There is no need to involve memory hotplug lock in kcompactd(), so let's add a new mutex to protect pgdat->kswapd accesses. Also, because the kcompactd task will check the state of kswapd task, it's better to call kcompactd_stop() before kswapd_stop() to reduce lock conflicts. [akpm@linux-foundation.org: add comments] Link: https://lkml.kernel.org/r/20220827111959.186838-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Cc: David Hildenbrand Cc: Muchun Song Signed-off-by: Andrew Morton --- include/linux/memory_hotplug.h | 20 ++++++++++++++++++++ include/linux/mmzone.h | 6 ++++-- mm/compaction.c | 14 +++++++++++++- mm/memory_hotplug.c | 2 +- mm/page_alloc.c | 1 + mm/vmscan.c | 27 ++++++++++++++++----------- 6 files changed, 55 insertions(+), 15 deletions(-) (limited to 'include/linux/memory_hotplug.h') diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 54675791bc50..51052969dbfe 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -215,6 +215,22 @@ void put_online_mems(void); void mem_hotplug_begin(void); void mem_hotplug_done(void); +/* See kswapd_is_running() */ +static inline void pgdat_kswapd_lock(pg_data_t *pgdat) +{ + mutex_lock(&pgdat->kswapd_lock); +} + +static inline void pgdat_kswapd_unlock(pg_data_t *pgdat) +{ + mutex_unlock(&pgdat->kswapd_lock); +} + +static inline void pgdat_kswapd_lock_init(pg_data_t *pgdat) +{ + mutex_init(&pgdat->kswapd_lock); +} + #else /* ! CONFIG_MEMORY_HOTPLUG */ #define pfn_to_online_page(pfn) \ ({ \ @@ -251,6 +267,10 @@ static inline bool movable_node_is_enabled(void) { return false; } + +static inline void pgdat_kswapd_lock(pg_data_t *pgdat) {} +static inline void pgdat_kswapd_unlock(pg_data_t *pgdat) {} +static inline void pgdat_kswapd_lock_init(pg_data_t *pgdat) {} #endif /* ! CONFIG_MEMORY_HOTPLUG */ /* diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index fd61347b4b1f..18cf0fc5ce67 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -956,8 +956,10 @@ typedef struct pglist_data { atomic_t nr_writeback_throttled;/* nr of writeback-throttled tasks */ unsigned long nr_reclaim_start; /* nr pages written while throttled * when throttling started. */ - struct task_struct *kswapd; /* Protected by - mem_hotplug_begin/done() */ +#ifdef CONFIG_MEMORY_HOTPLUG + struct mutex kswapd_lock; +#endif + struct task_struct *kswapd; /* Protected by kswapd_lock */ int kswapd_order; enum zone_type kswapd_highest_zoneidx; diff --git a/mm/compaction.c b/mm/compaction.c index 640fa76228dd..262c4676b32c 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1981,9 +1981,21 @@ static inline bool is_via_compact_memory(int order) return order == -1; } +/* + * Determine whether kswapd is (or recently was!) running on this node. + * + * pgdat_kswapd_lock() pins pgdat->kswapd, so a concurrent kswapd_stop() can't + * zero it. + */ static bool kswapd_is_running(pg_data_t *pgdat) { - return pgdat->kswapd && task_is_running(pgdat->kswapd); + bool running; + + pgdat_kswapd_lock(pgdat); + running = pgdat->kswapd && task_is_running(pgdat->kswapd); + pgdat_kswapd_unlock(pgdat); + + return running; } /* diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index dc727aee4ad3..9ae1f98548b1 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1940,8 +1940,8 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages, node_states_clear_node(node, &arg); if (arg.status_change_nid >= 0) { - kswapd_stop(node); kcompactd_stop(node); + kswapd_stop(node); } writeback_set_ratelimit(); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 1d4278115d71..09386b81e68e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7616,6 +7616,7 @@ static void __meminit pgdat_init_internals(struct pglist_data *pgdat) int i; pgdat_resize_init(pgdat); + pgdat_kswapd_lock_init(pgdat); pgdat_init_split_queue(pgdat); pgdat_init_kcompactd(pgdat); diff --git a/mm/vmscan.c b/mm/vmscan.c index bb993b21953d..02e720c83901 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4643,16 +4643,17 @@ void kswapd_run(int nid) { pg_data_t *pgdat = NODE_DATA(nid); - if (pgdat->kswapd) - return; - - pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); - if (IS_ERR(pgdat->kswapd)) { - /* failure at boot is fatal */ - BUG_ON(system_state < SYSTEM_RUNNING); - pr_err("Failed to start kswapd on node %d\n", nid); - pgdat->kswapd = NULL; + pgdat_kswapd_lock(pgdat); + if (!pgdat->kswapd) { + pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); + if (IS_ERR(pgdat->kswapd)) { + /* failure at boot is fatal */ + BUG_ON(system_state < SYSTEM_RUNNING); + pr_err("Failed to start kswapd on node %d\n", nid); + pgdat->kswapd = NULL; + } } + pgdat_kswapd_unlock(pgdat); } /* @@ -4661,12 +4662,16 @@ void kswapd_run(int nid) */ void kswapd_stop(int nid) { - struct task_struct *kswapd = NODE_DATA(nid)->kswapd; + pg_data_t *pgdat = NODE_DATA(nid); + struct task_struct *kswapd; + pgdat_kswapd_lock(pgdat); + kswapd = pgdat->kswapd; if (kswapd) { kthread_stop(kswapd); - NODE_DATA(nid)->kswapd = NULL; + pgdat->kswapd = NULL; } + pgdat_kswapd_unlock(pgdat); } static int __init kswapd_init(void) -- cgit v1.2.3 From f774a6a6fd39e1b5677bdf71f6813b382faddeeb Mon Sep 17 00:00:00 2001 From: Miaohe Lin Date: Fri, 16 Sep 2022 15:22:51 +0800 Subject: mm, memory_hotplug: remove obsolete generic_free_nodedata() Commit 390511e1476e ("mm, memory_hotplug: drop arch_free_nodedata") drops the last caller of generic_free_nodedata(). Remove it too. Link: https://lkml.kernel.org/r/20220916072257.9639-11-linmiaohe@huawei.com Signed-off-by: Miaohe Lin Reviewed-by: David Hildenbrand Reviewed-by: Anshuman Khandual Reviewed-by: Oscar Salvador Cc: Matthew Wilcox Signed-off-by: Andrew Morton --- include/linux/memory_hotplug.h | 8 -------- 1 file changed, 8 deletions(-) (limited to 'include/linux/memory_hotplug.h') diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 51052969dbfe..9fcbf5706595 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -43,11 +43,6 @@ extern void arch_refresh_nodedata(int nid, pg_data_t *pgdat); ({ \ memblock_alloc(sizeof(*pgdat), SMP_CACHE_BYTES); \ }) -/* - * This definition is just for error path in node hotadd. - * For node hotremove, we have to replace this. - */ -#define generic_free_nodedata(pgdat) kfree(pgdat) extern pg_data_t *node_data[]; static inline void arch_refresh_nodedata(int nid, pg_data_t *pgdat) @@ -63,9 +58,6 @@ static inline pg_data_t *generic_alloc_nodedata(int nid) BUG(); return NULL; } -static inline void generic_free_nodedata(pg_data_t *pgdat) -{ -} static inline void arch_refresh_nodedata(int nid, pg_data_t *pgdat) { } -- cgit v1.2.3