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a5f1783be2
In a later patch we want to add stackdepot support for object owner tracking in slub caches, which is enabled by slub_debug boot parameter. This creates a bootstrap problem as some caches are created early in boot when slab_is_available() is false and thus stack_depot_init() tries to use memblock. But, as reported by Hyeonggon Yoo [1] we are already beyond memblock_free_all(). Ideally memblock allocation should fail, yet it succeeds, but later the system crashes, which is a separately handled issue. To resolve this boostrap issue in a robust way, this patch adds another way to request stack_depot_early_init(), which happens at a well-defined point of time. In addition to build-time CONFIG_STACKDEPOT_ALWAYS_INIT, code that's e.g. processing boot parameters (which happens early enough) can call a new function stack_depot_want_early_init(), which sets a flag that stack_depot_early_init() will check. In this patch we also convert page_owner to this approach. While it doesn't have the bootstrap issue as slub, it's also a functionality enabled by a boot param and can thus request stack_depot_early_init() with memblock allocation instead of later initialization with kvmalloc(). As suggested by Mike, make stack_depot_early_init() only attempt memblock allocation and stack_depot_init() only attempt kvmalloc(). Also change the latter to kvcalloc(). In both cases we can lose the explicit array zeroing, which the allocations do already. As suggested by Marco, provide empty implementations of the init functions for !CONFIG_STACKDEPOT builds to simplify the callers. [1] https://lore.kernel.org/all/YhnUcqyeMgCrWZbd@ip-172-31-19-208.ap-northeast-1.compute.internal/ Reported-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Suggested-by: Mike Rapoport <rppt@linux.ibm.com> Suggested-by: Marco Elver <elver@google.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Marco Elver <elver@google.com> Reviewed-and-tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: David Rientjes <rientjes@google.com>
67 lines
2.1 KiB
C
67 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* A generic stack depot implementation
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*
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* Author: Alexander Potapenko <glider@google.com>
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* Copyright (C) 2016 Google, Inc.
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*
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* Based on code by Dmitry Chernenkov.
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*/
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#ifndef _LINUX_STACKDEPOT_H
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#define _LINUX_STACKDEPOT_H
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#include <linux/gfp.h>
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typedef u32 depot_stack_handle_t;
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depot_stack_handle_t __stack_depot_save(unsigned long *entries,
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unsigned int nr_entries,
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gfp_t gfp_flags, bool can_alloc);
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/*
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* Every user of stack depot has to call stack_depot_init() during its own init
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* when it's decided that it will be calling stack_depot_save() later. This is
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* recommended for e.g. modules initialized later in the boot process, when
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* slab_is_available() is true.
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*
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* The alternative is to select STACKDEPOT_ALWAYS_INIT to have stack depot
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* enabled as part of mm_init(), for subsystems where it's known at compile time
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* that stack depot will be used.
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*
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* Another alternative is to call stack_depot_want_early_init(), when the
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* decision to use stack depot is taken e.g. when evaluating kernel boot
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* parameters, which precedes the enablement point in mm_init().
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*
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* stack_depot_init() and stack_depot_want_early_init() can be called regardless
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* of CONFIG_STACKDEPOT and are no-op when disabled. The actual save/fetch/print
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* functions should only be called from code that makes sure CONFIG_STACKDEPOT
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* is enabled.
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*/
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#ifdef CONFIG_STACKDEPOT
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int stack_depot_init(void);
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void __init stack_depot_want_early_init(void);
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/* This is supposed to be called only from mm_init() */
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int __init stack_depot_early_init(void);
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#else
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static inline int stack_depot_init(void) { return 0; }
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static inline void stack_depot_want_early_init(void) { }
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static inline int stack_depot_early_init(void) { return 0; }
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#endif
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depot_stack_handle_t stack_depot_save(unsigned long *entries,
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unsigned int nr_entries, gfp_t gfp_flags);
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unsigned int stack_depot_fetch(depot_stack_handle_t handle,
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unsigned long **entries);
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int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
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int spaces);
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void stack_depot_print(depot_stack_handle_t stack);
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#endif
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