+ lib-stackdepot-use-page-allocator-if-both-slab-and-memblock-is-unavailable.patch added to -mm tree

* + lib-stackdepot-use-page-allocator-if-both-slab-and-memblock-is-unavailable.patch added to -mm tree
@ 2022-02-28  5:10 Andrew Morton
  2022-03-01  3:40 ` Hyeonggon Yoo
  0 siblings, 1 reply; 2+ messages in thread
From: Andrew Morton @ 2022-02-28  5:10 UTC (permalink / raw)
  To: mm-commits, yury.norov, vbabka, roman.gushchin, rientjes,
	qiang.zhang, penberg, mcroce, johannes.berg, jarkko,
	James.Bottomley, imran.f.khan, iamjoonsoo.kim, glittao, faiyazm,
	elver, edumazet, dvyukov, cl, arnd, andreyknvl, 42.hyeyoo, akpm


The patch titled
     Subject: lib/stackdepot: use page allocator if both slab and memblock is unavailable
has been added to the -mm tree.  Its filename is
     lib-stackdepot-use-page-allocator-if-both-slab-and-memblock-is-unavailable.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/lib-stackdepot-use-page-allocator-if-both-slab-and-memblock-is-unavailable.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/lib-stackdepot-use-page-allocator-if-both-slab-and-memblock-is-unavailable.patch

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------------------------------------------------------
From: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Subject: lib/stackdepot: use page allocator if both slab and memblock is unavailable

After commit 2dba5eb1c73b ("lib/stackdepot: allow optional init and
stack_table allocation by kvmalloc()"), stack_depot_init() is called later
if CONFIG_STACKDEPOT_ALWAYS_INIT=n to remove unnecessary memory usage.  It
allocates stack_table using memblock_alloc() or kvmalloc() depending on
availability of slab allocator.

But when stack_depot_init() is called while creating boot slab caches,
both slab allocator and memblock is not available.  So kernel crashes. 
Allocate stack_table from page allocator when both slab allocator and
memblock is unavailable.

Limit size of stack_table when using page allocator because vmalloc() is
also unavailable in kmem_cache_init().  It must not be larger than
(PAGE_SIZE << (MAX_ORDER - 1)).

This patch was tested on both CONFIG_STACKDEPOT_ALWAYS_INIT=y and n.

[lkp@intel.com: fix W=1 build warning]
Link: https://lkml.kernel.org/r/YhtDCoHWsF11rwze@ip-172-31-19-208.ap-northeast-1.compute.internal
Fixes: 2dba5eb1c73b ("lib/stackdepot: allow optional init and stack_table allocation by kvmalloc()")
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Oliver Glitta <glittao@gmail.com>
Cc: Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
Cc: Matteo Croce <mcroce@microsoft.com>
Cc: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Imran Khan <imran.f.khan@oracle.com>
Cc: Zqiang <qiang.zhang@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/stackdepot.c |   28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

--- a/lib/stackdepot.c~lib-stackdepot-use-page-allocator-if-both-slab-and-memblock-is-unavailable
+++ a/lib/stackdepot.c
@@ -73,6 +73,14 @@ static int next_slab_inited;
 static size_t depot_offset;
 static DEFINE_RAW_SPINLOCK(depot_lock);
 
+static size_t stack_hash_size = (1 << CONFIG_STACK_HASH_ORDER);
+static inline size_t stack_hash_mask(void)
+{
+	return stack_hash_size - 1;
+}
+
+#define STACK_HASH_SEED 0x9747b28c
+
 static bool init_stack_slab(void **prealloc)
 {
 	if (!*prealloc)
@@ -142,10 +150,6 @@ depot_alloc_stack(unsigned long *entries
 	return stack;
 }
 
-#define STACK_HASH_SIZE (1L << CONFIG_STACK_HASH_ORDER)
-#define STACK_HASH_MASK (STACK_HASH_SIZE - 1)
-#define STACK_HASH_SEED 0x9747b28c
-
 static bool stack_depot_disable;
 static struct stack_record **stack_table;
 
@@ -172,18 +176,28 @@ __ref int stack_depot_init(void)
 
 	mutex_lock(&stack_depot_init_mutex);
 	if (!stack_depot_disable && !stack_table) {
-		size_t size = (STACK_HASH_SIZE * sizeof(struct stack_record *));
+		size_t size = (stack_hash_size * sizeof(struct stack_record *));
 		int i;
 
 		if (slab_is_available()) {
 			pr_info("Stack Depot allocating hash table with kvmalloc\n");
 			stack_table = kvmalloc(size, GFP_KERNEL);
+		} else if (totalram_pages() > 0) {
+			/* Reduce size because vmalloc may be unavailable */
+			size = min_t(size_t, size, PAGE_SIZE << (MAX_ORDER - 1));
+			stack_hash_size = size / sizeof(struct stack_record *);
+
+			pr_info("Stack Depot allocating hash table with __get_free_pages\n");
+			stack_table = (struct stack_record **)
+				      __get_free_pages(GFP_KERNEL, get_order(size));
 		} else {
 			pr_info("Stack Depot allocating hash table with memblock_alloc\n");
 			stack_table = memblock_alloc(size, SMP_CACHE_BYTES);
 		}
+
 		if (stack_table) {
-			for (i = 0; i < STACK_HASH_SIZE;  i++)
+			pr_info("Stack Depot hash table size=%zu\n", stack_hash_size);
+			for (i = 0; i < stack_hash_size;  i++)
 				stack_table[i] = NULL;
 		} else {
 			pr_err("Stack Depot hash table allocation failed, disabling\n");
@@ -363,7 +377,7 @@ depot_stack_handle_t __stack_depot_save(
 		goto fast_exit;
 
 	hash = hash_stack(entries, nr_entries);
-	bucket = &stack_table[hash & STACK_HASH_MASK];
+	bucket = &stack_table[hash & stack_hash_mask()];
 
 	/*
 	 * Fast path: look the stack trace up without locking.
_

Patches currently in -mm which might be from 42.hyeyoo@gmail.com are

lib-stackdepot-use-page-allocator-if-both-slab-and-memblock-is-unavailable.patch


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