user/sven/linux.git/include/linux/slab.h, branch v5.12-rc2

mm: Add mem_dump_obj() to print source of memory block

2021-01-22T23:16:01Z

There are kernel facilities such as per-CPU reference counts that give error messages in generic handlers or callbacks, whose messages are unenlightening. In the case of per-CPU reference-count underflow, this is not a problem when creating a new use of this facility because in that case the bug is almost certainly in the code implementing that new use. However, trouble arises when deploying across many systems, which might exercise corner cases that were not seen during development and testing. Here, it would be really nice to get some kind of hint as to which of several uses the underflow was caused by. This commit therefore exposes a mem_dump_obj() function that takes a pointer to memory (which must still be allocated if it has been dynamically allocated) and prints available information on where that memory came from. This pointer can reference the middle of the block as well as the beginning of the block, as needed by things like RCU callback functions and timer handlers that might not know where the beginning of the memory block is. These functions and handlers can use mem_dump_obj() to print out better hints as to where the problem might lie. The information printed can depend on kernel configuration. For example, the allocation return address can be printed only for slab and slub, and even then only when the necessary debug has been enabled. For slab, build with CONFIG_DEBUG_SLAB=y, and either use sizes with ample space to the next power of two or use the SLAB_STORE_USER when creating the kmem_cache structure. For slub, build with CONFIG_SLUB_DEBUG=y and boot with slub_debug=U, or pass SLAB_STORE_USER to kmem_cache_create() if more focused use is desired. Also for slub, use CONFIG_STACKTRACE to enable printing of the allocation-time stack trace. Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Andrew Morton Cc: Reported-by: Andrii Nakryiko [ paulmck: Convert to printing and change names per Joonsoo Kim. ] [ paulmck: Move slab definition per Stephen Rothwell and kbuild test robot. ] [ paulmck: Handle CONFIG_MMU=n case where vmalloc() is kmalloc(). ] [ paulmck: Apply Vlastimil Babka feedback on slab.c kmem_provenance(). ] [ paulmck: Extract more info from !SLUB_DEBUG per Joonsoo Kim. ] [ paulmck: Explicitly check for small pointers per Naresh Kamboju. ] Acked-by: Joonsoo Kim Acked-by: Vlastimil Babka Tested-by: Naresh Kamboju Signed-off-by: Paul E. McKenney

mm: slab: provide krealloc_array()

2020-12-15T20:13:37Z

When allocating an array of elements, users should check for multiplication overflow or preferably use one of the provided helpers like: kmalloc_array(). There's no krealloc_array() counterpart but there are many users who use regular krealloc() to reallocate arrays. Let's provide an actual krealloc_array() implementation. While at it: add some documentation regarding krealloc. Link: https://lkml.kernel.org/r/20201109110654.12547-3-brgl@bgdev.pl Signed-off-by: Bartosz Golaszewski Acked-by: Vlastimil Babka Cc: Alexander Shishkin Cc: Andy Shevchenko Cc: Borislav Petkov Cc: Borislav Petkov Cc: Christian Knig Cc: Christoph Lameter Cc: Daniel Vetter Cc: Daniel Vetter Cc: David Airlie Cc: David Rientjes Cc: Gustavo Padovan Cc: James Morse Cc: Jaroslav Kysela Cc: Jason Wang Cc: Joonsoo Kim Cc: Linus Walleij Cc: Maarten Lankhorst Cc: Mauro Carvalho Chehab Cc: Maxime Ripard Cc: "Michael S . Tsirkin" Cc: Pekka Enberg Cc: Robert Richter Cc: Sumit Semwal Cc: Takashi Iwai Cc: Takashi Iwai Cc: Thomas Zimmermann Cc: Tony Luck Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: remove kzfree() compatibility definition

2020-10-25T18:39:02Z

Commit 453431a54934 ("mm, treewide: rename kzfree() to kfree_sensitive()") renamed kzfree() to kfree_sensitive(), but it left a compatibility definition of kzfree() to avoid being too disruptive. Since then a few more instances of kzfree() have slipped in. Just get rid of them and remove the compatibility definition once and for all. Signed-off-by: Eric Biggers Signed-off-by: Linus Torvalds

include/linux/slab.h: fix a typo error in comment

2020-10-14T01:38:27Z

fix a typo error in slab.h "allocagtor" -> "allocator" Signed-off-by: tangjianqiang Signed-off-by: Andrew Morton Acked-by: Souptick Joarder Link: https://lkml.kernel.org/r/1600230053-24303-1-git-send-email-tangjianqiang@xiaomi.com Signed-off-by: Linus Torvalds

mm: memcg/slab: use a single set of kmem_caches for all allocations

2020-08-07T18:33:25Z

Instead of having two sets of kmem_caches: one for system-wide and non-accounted allocations and the second one shared by all accounted allocations, we can use just one. The idea is simple: space for obj_cgroup metadata can be allocated on demand and filled only for accounted allocations. It allows to remove a bunch of code which is required to handle kmem_cache clones for accounted allocations. There is no more need to create them, accumulate statistics, propagate attributes, etc. It's a quite significant simplification. Also, because the total number of slab_caches is reduced almost twice (not all kmem_caches have a memcg clone), some additional memory savings are expected. On my devvm it additionally saves about 3.5% of slab memory. [guro@fb.com: fix build on MIPS] Link: http://lkml.kernel.org/r/20200717214810.3733082-1-guro@fb.com Suggested-by: Johannes Weiner Signed-off-by: Roman Gushchin Signed-off-by: Andrew Morton Reviewed-by: Vlastimil Babka Reviewed-by: Shakeel Butt Cc: Christoph Lameter Cc: Michal Hocko Cc: Tejun Heo Cc: Naresh Kamboju Link: http://lkml.kernel.org/r/20200623174037.3951353-18-guro@fb.com Signed-off-by: Linus Torvalds

mm: memcg/slab: use a single set of kmem_caches for all accounted allocations

2020-08-07T18:33:25Z

This is fairly big but mostly red patch, which makes all accounted slab allocations use a single set of kmem_caches instead of creating a separate set for each memory cgroup. Because the number of non-root kmem_caches is now capped by the number of root kmem_caches, there is no need to shrink or destroy them prematurely. They can be perfectly destroyed together with their root counterparts. This allows to dramatically simplify the management of non-root kmem_caches and delete a ton of code. This patch performs the following changes: 1) introduces memcg_params.memcg_cache pointer to represent the kmem_cache which will be used for all non-root allocations 2) reuses the existing memcg kmem_cache creation mechanism to create memcg kmem_cache on the first allocation attempt 3) memcg kmem_caches are named -memcg, e.g. dentry-memcg 4) simplifies memcg_kmem_get_cache() to just return memcg kmem_cache or schedule it's creation and return the root cache 5) removes almost all non-root kmem_cache management code (separate refcounter, reparenting, shrinking, etc) 6) makes slab debugfs to display root_mem_cgroup css id and never show :dead and :deact flags in the memcg_slabinfo attribute. Following patches in the series will simplify the kmem_cache creation. Signed-off-by: Roman Gushchin Signed-off-by: Andrew Morton Reviewed-by: Vlastimil Babka Reviewed-by: Shakeel Butt Cc: Christoph Lameter Cc: Johannes Weiner Cc: Michal Hocko Cc: Tejun Heo Link: http://lkml.kernel.org/r/20200623174037.3951353-13-guro@fb.com Signed-off-by: Linus Torvalds

mm, treewide: rename kzfree() to kfree_sensitive()

2020-08-07T18:33:22Z

As said by Linus: A symmetric naming is only helpful if it implies symmetries in use. Otherwise it's actively misleading. In "kzalloc()", the z is meaningful and an important part of what the caller wants. In "kzfree()", the z is actively detrimental, because maybe in the future we really _might_ want to use that "memfill(0xdeadbeef)" or something. The "zero" part of the interface isn't even _relevant_. The main reason that kzfree() exists is to clear sensitive information that should not be leaked to other future users of the same memory objects. Rename kzfree() to kfree_sensitive() to follow the example of the recently added kvfree_sensitive() and make the intention of the API more explicit. In addition, memzero_explicit() is used to clear the memory to make sure that it won't get optimized away by the compiler. The renaming is done by using the command sequence: git grep -w --name-only kzfree |\ xargs sed -i 's/kzfree/kfree_sensitive/' followed by some editing of the kfree_sensitive() kerneldoc and adding a kzfree backward compatibility macro in slab.h. [akpm@linux-foundation.org: fs/crypto/inline_crypt.c needs linux/slab.h] [akpm@linux-foundation.org: fix fs/crypto/inline_crypt.c some more] Suggested-by: Joe Perches Signed-off-by: Waiman Long Signed-off-by: Andrew Morton Acked-by: David Howells Acked-by: Michal Hocko Acked-by: Johannes Weiner Cc: Jarkko Sakkinen Cc: James Morris Cc: "Serge E. Hallyn" Cc: Joe Perches Cc: Matthew Wilcox Cc: David Rientjes Cc: Dan Carpenter Cc: "Jason A . Donenfeld" Link: http://lkml.kernel.org/r/20200616154311.12314-3-longman@redhat.com Signed-off-by: Linus Torvalds

docs: mm: slab.h: fix a broken cross-reference

2020-04-10T22:36:20Z

There is a typo at the cross-reference link, causing this warning: include/linux/slab.h:11: WARNING: undefined label: memory-allocation (if the link has no caption the label must precede a section header) Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Andrew Morton Cc: Jonathan Corbet Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Link: http://lkml.kernel.org/r/0aeac24235d356ebd935d11e147dcc6edbb6465c.1586359676.git.mchehab+huawei@kernel.org Signed-off-by: Linus Torvalds

mm: remove __krealloc

2020-02-04T03:05:24Z

Since 5.5-rc1 the last user of this function is gone, so remove the functionality. See commit 2ad9d7747c10 ("netfilter: conntrack: free extension area immediately") for details. Link: http://lkml.kernel.org/r/20191212223442.22141-1-fw@strlen.de Signed-off-by: Florian Westphal Acked-by: Andrew Morton Acked-by: David Rientjes Reviewed-by: David Hildenbrand Cc: Christoph Lameter Cc: Pekka Enberg Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, slab: remove unused kmalloc_size()

2019-12-01T14:29:17Z

The size of kmalloc can be obtained from kmalloc_info[], so remove kmalloc_size() that will not be used anymore. Link: http://lkml.kernel.org/r/1569241648-26908-3-git-send-email-lpf.vector@gmail.com Signed-off-by: Pengfei Li Acked-by: Vlastimil Babka Acked-by: Roman Gushchin Acked-by: David Rientjes Cc: Christoph Lameter Cc: Joonsoo Kim Cc: Pekka Enberg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds