mm, slub: prevent kmalloc_node crashes and memory leaks

tehcaster · gregkh · commit a8a2622689c4 · 2020-04-02T17:20:26.000+02:00
commit 0715e6c upstream. Sachin reports [1] a crash in SLUB __slab_alloc(): BUG: Kernel NULL pointer dereference on read at 0x000073b0 Faulting instruction address: 0xc0000000003d55f4 Oops: Kernel access of bad area, sig: 11 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries Modules linked in: CPU: 19 PID: 1 Comm: systemd Not tainted 5.6.0-rc2-next-20200218-autotest #1 NIP: c0000000003d55f4 LR: c0000000003d5b94 CTR: 0000000000000000 REGS: c0000008b37836d0 TRAP: 0300 Not tainted (5.6.0-rc2-next-20200218-autotest) MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 24004844 XER: 00000000 CFAR: c00000000000dec4 DAR: 00000000000073b0 DSISR: 40000000 IRQMASK: 1 GPR00: c0000000003d5b94 c0000008b3783960 c00000000155d400 c0000008b301f500 GPR04: 0000000000000dc0 0000000000000002 c0000000003443d8 c0000008bb398620 GPR08: 00000008ba2f0000 0000000000000001 0000000000000000 0000000000000000 GPR12: 0000000024004844 c00000001ec52a00 0000000000000000 0000000000000000 GPR16: c0000008a1b20048 c000000001595898 c000000001750c18 0000000000000002 GPR20: c000000001750c28 c000000001624470 0000000fffffffe0 5deadbeef0000122 GPR24: 0000000000000001 0000000000000dc0 0000000000000002 c0000000003443d8 GPR28: c0000008b301f500 c0000008bb398620 0000000000000000 c00c000002287180 NIP ___slab_alloc+0x1f4/0x760 LR __slab_alloc+0x34/0x60 Call Trace: ___slab_alloc+0x334/0x760 (unreliable) __slab_alloc+0x34/0x60 __kmalloc_node+0x110/0x490 kvmalloc_node+0x58/0x110 mem_cgroup_css_online+0x108/0x270 online_css+0x48/0xd0 cgroup_apply_control_enable+0x2ec/0x4d0 cgroup_mkdir+0x228/0x5f0 kernfs_iop_mkdir+0x90/0xf0 vfs_mkdir+0x110/0x230 do_mkdirat+0xb0/0x1a0 system_call+0x5c/0x68 This is a PowerPC platform with following NUMA topology: available: 2 nodes (0-1) node 0 cpus: node 0 size: 0 MB node 0 free: 0 MB node 1 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 node 1 size: 35247 MB node 1 free: 30907 MB node distances: node 0 1 0: 10 40 1: 40 10 possible numa nodes: 0-31 This only happens with a mmotm patch "mm/memcontrol.c: allocate shrinker_map on appropriate NUMA node" [2] which effectively calls kmalloc_node for each possible node. SLUB however only allocates kmem_cache_node on online N_NORMAL_MEMORY nodes, and relies on node_to_mem_node to return such valid node for other nodes since commit a561ce0 ("slub: fall back to node_to_mem_node() node if allocating on memoryless node"). This is however not true in this configuration where the _node_numa_mem_ array is not initialized for nodes 0 and 2-31, thus it contains zeroes and get_partial() ends up accessing non-allocated kmem_cache_node. A related issue was reported by Bharata (originally by Ramachandran) [3] where a similar PowerPC configuration, but with mainline kernel without patch [2] ends up allocating large amounts of pages by kmalloc-1k kmalloc-512. This seems to have the same underlying issue with node_to_mem_node() not behaving as expected, and might probably also lead to an infinite loop with CONFIG_SLUB_CPU_PARTIAL [4]. This patch should fix both issues by not relying on node_to_mem_node() anymore and instead simply falling back to NUMA_NO_NODE, when kmalloc_node(node) is attempted for a node that's not online, or has no usable memory. The "usable memory" condition is also changed from node_present_pages() to N_NORMAL_MEMORY node state, as that is exactly the condition that SLUB uses to allocate kmem_cache_node structures. The check in get_partial() is removed completely, as the checks in ___slab_alloc() are now sufficient to prevent get_partial() being reached with an invalid node. [1] https://lore.kernel.org/linux-next/3381CD91-AB3D-4773-BA04-E7A072A63968@linux.vnet.ibm.com/ [2] https://lore.kernel.org/linux-mm/fff0e636-4c36-ed10-281c-8cdb0687c839@virtuozzo.com/ [3] https://lore.kernel.org/linux-mm/20200317092624.GB22538@in.ibm.com/ [4] https://lore.kernel.org/linux-mm/088b5996-faae-8a56-ef9c-5b567125ae54@suse.cz/ Fixes: a561ce0 ("slub: fall back to node_to_mem_node() node if allocating on memoryless node") Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com> Reported-by: PUVICHAKRAVARTHY RAMACHANDRAN <puvichakravarthy@in.ibm.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com> Tested-by: Bharata B Rao <bharata@linux.ibm.com> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christopher Lameter <cl@linux.com> Cc: linuxppc-dev@lists.ozlabs.org Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Nathan Lynch <nathanl@linux.ibm.com> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/20200320115533.9604-1-vbabka@suse.cz Debugged-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/mm/slub.c b/mm/slub.c
@@ -1909,8 +1909,6 @@ static void *get_partial(struct kmem_cache *s, gfp_t flags, int node,
 
 	if (node == NUMA_NO_NODE)
 		searchnode = numa_mem_id();
-	else if (!node_present_pages(node))
-		searchnode = node_to_mem_node(node);
 
 	object = get_partial_node(s, get_node(s, searchnode), c, flags);
 	if (object || node != NUMA_NO_NODE)
@@ -2506,17 +2504,27 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
 	struct page *page;
 
 	page = c->page;
-	if (!page)
+	if (!page) {
+		/*
+		 * if the node is not online or has no normal memory, just
+		 * ignore the node constraint
+		 */
+		if (unlikely(node != NUMA_NO_NODE &&
+			     !node_state(node, N_NORMAL_MEMORY)))
+			node = NUMA_NO_NODE;
 		goto new_slab;
+	}
 redo:
 
 	if (unlikely(!node_match(page, node))) {
-		int searchnode = node;
-
-		if (node != NUMA_NO_NODE && !node_present_pages(node))
-			searchnode = node_to_mem_node(node);
-
-		if (unlikely(!node_match(page, searchnode))) {
+		/*
+		 * same as above but node_match() being false already
+		 * implies node != NUMA_NO_NODE
+		 */
+		if (!node_state(node, N_NORMAL_MEMORY)) {
+			node = NUMA_NO_NODE;
+			goto redo;
+		} else {
 			stat(s, ALLOC_NODE_MISMATCH);
 			deactivate_slab(s, page, c->freelist);
 			c->page = NULL;
