- 04 Jun, 2020 40 commits
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Charan Teja Reddy authored
Updating the zone watermarks by any means, like min_free_kbytes, water_mark_scale_factor etc, when ->watermark_boost is set will result in higher low and high watermarks than the user asked. Below are the steps to reproduce the problem on system setup of Android kernel running on Snapdragon hardware. 1) Default settings of the system are as below: #cat /proc/sys/vm/min_free_kbytes = 5162 #cat /proc/zoneinfo | grep -e boost -e low -e "high " -e min -e Node Node 0, zone Normal min 797 low 8340 high 8539 2) Monitor the zone->watermark_boost(by adding a debug print in the kernel) and whenever it is greater than zero value, write the same value of min_free_kbytes obtained from step 1. #echo 5162 > /proc/sys/vm/min_free_kbytes 3) Then read the zone watermarks in the system while the ->watermark_boost is zero. This should show the same values of watermarks as step 1 but shown a higher values than asked. #cat /proc/zoneinfo | grep -e boost -e low -e "high " -e min -e Node Node 0, zone Normal min 797 low 21148 high 21347 These higher values are because of updating the zone watermarks using the macro min_wmark_pages(zone) which also adds the zone->watermark_boost. #define min_wmark_pages(z) (z->_watermark[WMARK_MIN] + z->watermark_boost) So the steps that lead to the issue are: 1) On the extfrag event, watermarks are boosted by storing the required value in ->watermark_boost. 2) User tries to update the zone watermarks level in the system through min_free_kbytes or watermark_scale_factor. 3) Later, when kswapd woke up, it resets the zone->watermark_boost to zero. In step 2), we use the min_wmark_pages() macro to store the watermarks in the zone structure thus the values are always offsetted by ->watermark_boost value. This can be avoided by resetting the ->watermark_boost to zero before it is used. Signed-off-by:
Charan Teja Reddy <charante@codeaurora.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Reviewed-by:
Baoquan He <bhe@redhat.com> Cc: Vinayak Menon <vinmenon@codeaurora.org> Link: http://lkml.kernel.org/r/1589457511-4255-1-git-send-email-charante@codeaurora.orgSigned-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Sandipan Das authored
Initially, the per-cpu pagesets of each zone are set to the boot pagesets. The real pagesets are allocated later but before that happens, page allocations do occur and the numa stats for the boot pagesets get incremented since they are common to all zones at that point. The real pagesets, however, are allocated for the populated zones only. Unpopulated zones, like those associated with memory-less nodes, continue using the boot pageset and end up skewing the numa stats of the corresponding node. E.g. $ numactl -H available: 2 nodes (0-1) node 0 cpus: 0 1 2 3 node 0 size: 0 MB node 0 free: 0 MB node 1 cpus: 4 5 6 7 node 1 size: 8131 MB node 1 free: 6980 MB node distances: node 0 1 0: 10 40 1: 40 10 $ numastat node0 node1 numa_hit 108 56495 numa_miss 0 0 numa_foreign 0 0 interleave_hit 0 4537 local_node 108 31547 other_node 0 24948 Hence, the boot pageset stats need to be cleared after the real pagesets are allocated. After this point, the stats of the boot pagesets do not change as page allocations requested for a memory-less node will either fail (if __GFP_THISNODE is used) or get fulfilled by a preferred zone of a different node based on the fallback zonelist. [sandipan@linux.ibm.com: v3] Link: http://lkml.kernel.org/r/20200511170356.162531-1-sandipan@linux.ibm.comSigned-off-by:Sandipan Das <sandipan@linux.ibm.com> Signed-off-by:
Vlastimil Babka <vbabka@suse.cz> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Link: http://lkml.kernel.org/r/9c9c2d1b15e37f6e6bf32f99e3100035e90c4ac9.1588868430.git.sandipan@linux.ibm.comSigned-off-by:
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Wei Yang authored
Pageblock migrate type is encoded in GFP flags, just as zone_type and zonelist. Currently we use gfp_zone() and gfp_zonelist() to extract related information, it would be proper to use the same naming convention for migrate type. Signed-off-by:
Wei Yang <richard.weiyang@gmail.com> Signed-off-by:
Pankaj Gupta <pankaj.gupta.linux@gmail.com> Link: http://lkml.kernel.org/r/20200329080823.7735-1-richard.weiyang@gmail.comSigned-off-by:
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Wei Yang authored
Slightly simplify the code by initializing user_mask with NODE_MASK_NONE, instead of later calling nodes_clear(). This saves a line of code. Signed-off-by:
John Hubbard <jhubbard@nvidia.com> Reviewed-by:
David Hildenbrand <david@redhat.com> Reviewed-by:
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Joonsoo Kim authored
classzone_idx is just different name for high_zoneidx now. So, integrate them and add some comment to struct alloc_context in order to reduce future confusion about the meaning of this variable. The accessor, ac_classzone_idx() is also removed since it isn't needed after integration. In addition to integration, this patch also renames high_zoneidx to highest_zoneidx since it represents more precise meaning. Signed-off-by:
Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by:
David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Ye Xiaolong <xiaolong.ye@intel.com> Link: http://lkml.kernel.org/r/1587095923-7515-3-git-send-email-iamjoonsoo.kim@lge.comSigned-off-by:
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Joonsoo Kim authored
Patch series "integrate classzone_idx and high_zoneidx", v5. This patchset is followup of the problem reported and discussed two years ago [1, 2]. The problem this patchset solves is related to the classzone_idx on the NUMA system. It causes a problem when the lowmem reserve protection exists for some zones on a node that do not exist on other nodes. This problem was reported two years ago, and, at that time, the solution got general agreements [2]. But it was not upstreamed. [1]: http://lkml.kernel.org/r/20180102063528.GG30397@yexl-desktop [2]: http://lkml.kernel.org/r/1525408246-14768-1-git-send-email-iamjoonsoo.kim@lge.com This patch (of 2): Currently, we use classzone_idx to calculate lowmem reserve proetection for an allocation request. This classzone_idx causes a problem on NUMA systems when the lowmem reserve protection exists for some zones on a node that do not exist on other nodes. Before further explanation, I should first clarify how to compute the classzone_idx and the high_zoneidx. - ac->high_zoneidx is computed via the arcane gfp_zone(gfp_mask) and represents the index of the highest zone the allocation can use - classzone_idx was supposed to be the index of the highest zone on the local node that the allocation can use, that is actually available in the system Think about following example. Node 0 has 4 populated zone, DMA/DMA32/NORMAL/MOVABLE. Node 1 has 1 populated zone, NORMAL. Some zones, such as MOVABLE, doesn't exist on node 1 and this makes following difference. Assume that there is an allocation request whose gfp_zone(gfp_mask) is the zone, MOVABLE. Then, it's high_zoneidx is 3. If this allocation is initiated on node 0, it's classzone_idx is 3 since actually available/usable zone on local (node 0) is MOVABLE. If this allocation is initiated on node 1, it's classzone_idx is 2 since actually available/usable zone on local (node 1) is NORMAL. You can see that classzone_idx of the allocation request are different according to their starting node, even if their high_zoneidx is the same. Think more about these two allocation requests. If they are processed on local, there is no problem. However, if allocation is initiated on node 1 are processed on remote, in this example, at the NORMAL zone on node 0, due to memory shortage, problem occurs. Their different classzone_idx leads to different lowmem reserve and then different min watermark. See the following example. root@ubuntu:/sys/devices/system/memory# cat /proc/zoneinfo Node 0, zone DMA per-node stats ... pages free 3965 min 5 low 8 high 11 spanned 4095 present 3998 managed 3977 protection: (0, 2961, 4928, 5440) ... Node 0, zone DMA32 pages free 757955 min 1129 low 1887 high 2645 spanned 1044480 present 782303 managed 758116 protection: (0, 0, 1967, 2479) ... Node 0, zone Normal pages free 459806 min 750 low 1253 high 1756 spanned 524288 present 524288 managed 503620 protection: (0, 0, 0, 4096) ... Node 0, zone Movable pages free 130759 min 195 low 326 high 457 spanned 1966079 present 131072 managed 131072 protection: (0, 0, 0, 0) ... Node 1, zone DMA pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 protection: (0, 0, 1006, 1006) Node 1, zone DMA32 pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 protection: (0, 0, 1006, 1006) Node 1, zone Normal per-node stats ... pages free 233277 min 383 low 640 high 897 spanned 262144 present 262144 managed 257744 protection: (0, 0, 0, 0) ... Node 1, zone Movable pages free 0 min 0 low 0 high 0 spanned 262144 present 0 managed 0 protection: (0, 0, 0, 0) - static min watermark for the NORMAL zone on node 0 is 750. - lowmem reserve for the request with classzone idx 3 at the NORMAL on node 0 is 4096. - lowmem reserve for the request with classzone idx 2 at the NORMAL on node 0 is 0. So, overall min watermark is: allocation initiated on node 0 (classzone_idx 3): 750 + 4096 = 4846 allocation initiated on node 1 (classzone_idx 2): 750 + 0 = 750 Allocation initiated on node 1 will have some precedence than allocation initiated on node 0 because min watermark of the former allocation is lower than the other. So, allocation initiated on node 1 could succeed on node 0 when allocation initiated on node 0 could not, and, this could cause too many numa_miss allocation. Then, performance could be downgraded. Recently, there was a regression report about this problem on CMA patches since CMA memory are placed in ZONE_MOVABLE by those patches. I checked that problem is disappeared with this fix that uses high_zoneidx for classzone_idx. http://lkml.kernel.org/r/20180102063528.GG30397@yexl-desktop Using high_zoneidx for classzone_idx is more consistent way than previous approach because system's memory layout doesn't affect anything to it. With this patch, both classzone_idx on above example will be 3 so will have the same min watermark. allocation initiated on node 0: 750 + 4096 = 4846 allocation initiated on node 1: 750 + 4096 = 4846 One could wonder if there is a side effect that allocation initiated on node 1 will use higher bar when allocation is handled on local since classzone_idx could be higher than before. It will not happen because the zone without managed page doesn't contributes lowmem_reserve at all. Reported-by:
Ye Xiaolong <xiaolong.ye@intel.com> Signed-off-by:
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Baoquan He authored
Because the lowmem reserve protection of a zone can't tell anything if the zone is empty, except of adding one more line in /proc/zoneinfo. Let's remove it from that zone's showing. Signed-off-by:
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Baoquan He authored
When requesting memory allocation from a specific zone is not satisfied, it will fall to lower zone to try allocating memory. In this case, lower zone's ->lowmem_reserve[] will help protect its own memory resource. The higher the relevant ->lowmem_reserve[] is, the harder the upper zone can get memory from this lower zone. However, this protection mechanism should be applied to populated zone, but not an empty zone. So filling ->lowmem_reserve[] for empty zone is not necessary, and may mislead people that it's valid data in that zone. Node 2, zone DMA pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 protection: (0, 0, 1024, 1024) Node 2, zone DMA32 pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 protection: (0, 0, 1024, 1024) Node 2, zone Normal per-node stats nr_inactive_anon 0 nr_active_anon 143 nr_inactive_file 0 nr_active_file 0 nr_unevictable 0 nr_slab_reclaimable 45 nr_slab_unreclaimable 254 Here clear out zone->lowmem_reserve[] if zone is empty. Signed-off-by: -
Baoquan He authored
Patch series "improvements about lowmem_reserve and /proc/zoneinfo", v2. This patch (of 3): When people write to /proc/sys/vm/lowmem_reserve_ratio to change sysctl_lowmem_reserve_ratio[], setup_per_zone_lowmem_reserve() is called to recalculate all ->lowmem_reserve[] for each zone of all nodes as below: static void setup_per_zone_lowmem_reserve(void) { ... for_each_online_pgdat(pgdat) { for (j = 0; j < MAX_NR_ZONES; j++) { ... while (idx) { ... if (sysctl_lowmem_reserve_ratio[idx] < 1) { sysctl_lowmem_reserve_ratio[idx] = 0; lower_zone->lowmem_reserve[j] = 0; } else { ... } } } } Meanwhile, here, sysctl_lowmem_reserve_ratio[idx] will be tuned if its value is smaller than '1'. As we know, sysctl_lowmem_reserve_ratio[] is set for zone without regarding to which node it belongs to. That means the tuning will be done on all nodes, even though it has been done in the first node. And the tuning will be done too even when init_per_zone_wmark_min() calls setup_per_zone_lowmem_reserve(), where actually nobody tries to change sysctl_lowmem_reserve_ratio[]. So now move the tuning into lowmem_reserve_ratio_sysctl_handler(), to make code logic more reasonable. Signed-off-by: -
Baoquan He authored
Since commit 397dc00e ("mips: sgi-ip27: switch from DISCONTIGMEM to SPARSEMEM"), the last caller of free_bootmem_with_active_regions() was gone. Now no user calls it any more. Let's remove it. Signed-off-by:
Michal Hocko <mhocko@suse.com> Link: http://lkml.kernel.org/r/20200402143455.5145-1-bhe@redhat.comSigned-off-by:
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Roman Gushchin authored
Currently a cma area is barely used by the page allocator because it's used only as a fallback from movable, however kswapd tries hard to make sure that the fallback path isn't used. This results in a system evicting memory and pushing data into swap, while lots of CMA memory is still available. This happens despite the fact that alloc_contig_range is perfectly capable of moving any movable allocations out of the way of an allocation. To effectively use the cma area let's alter the rules: if the zone has more free cma pages than the half of total free pages in the zone, use cma pageblocks first and fallback to movable blocks in the case of failure. [guro@fb.com: ifdef the cma-specific code] Link: http://lkml.kernel.org/r/20200311225832.GA178154@carbon.DHCP.thefacebook.comCo-developed-by:
Rik van Riel <riel@surriel.com> Signed-off-by:
Roman Gushchin <guro@fb.com> Signed-off-by:
Minchan Kim <minchan@kernel.org> Cc: Qian Cai <cai@lca.pw> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200306150102.3e77354b@imladris.surriel.comSigned-off-by:
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Wei Yang authored
We share similar code in check_[new|free]_page_bad() to get the page's bad reason. Let's extract it and reduce code duplication. Signed-off-by:
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Wei Yang authored
free_pages_check() is the counterpart of check_new_page(). Rename it to use the same naming convention. Signed-off-by:
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Wei Yang authored
free_pages_check_bad() is the counterpart of check_new_page_bad(). Rename it to use the same naming convention. Signed-off-by:
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Wei Yang authored
After commit 5b57b8f2 ("mm/debug.c: always print flags in dump_page()"), page->flags is always printed for a bad page. It is not necessary to have bad_flags any more. Suggested-by:
Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by:
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Wei Yang authored
Patch series "mm/page_alloc.c: cleanup on check page", v3. This patchset does some cleanup related to check page. 1. Remove unnecessary bad_reason assignment 2. Remove bad_flags to bad_page() 3. Rename function for naming convention 4. Extract common part to check page Thanks for suggestions from David Rientjes and Anshuman Khandual. This patch (of 5): Since function returns directly, bad_[reason|flags] is not used any where. And move this to the first. This is a following cleanup for commit e570f56c ("mm: check_new_page_bad() directly returns in __PG_HWPOISON case") Signed-off-by:
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Mike Rapoport authored
To reflect the updates to free_area_init() family of functions. Signed-off-by:
Mike Rapoport <rppt@linux.ibm.com> Signed-off-by:
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Mike Rapoport authored
find_min_pfn_with_active_regions() calls find_min_pfn_for_node() with nid parameter set to MAX_NUMNODES. This makes the find_min_pfn_for_node() traverse all memblock memory regions although the first PFN in the system can be easily found with memblock_start_of_DRAM(). Use memblock_start_of_DRAM() in find_min_pfn_with_active_regions() and drop now unused find_min_pfn_for_node(). Signed-off-by:
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Mike Rapoport authored
free_area_init_node() now always uses memblock info and the zone PFN limits so it does not need the backwards compatibility functions to calculate the zone spanned and absent pages. The removal of the compat_ versions of zone_{abscent,spanned}_pages_in_node() in turn, makes zone_size and zhole_size parameters unused. The node_start_pfn is determined by get_pfn_range_for_nid(), so there is no need to pass it to free_area_init_node(). As a result, the only required parameter to free_area_init_node() is the node ID, all the rest are removed along with no longer used compat_zone_{abscent,spanned}_pages_in_node() helpers. Signed-off-by: -
Mike Rapoport authored
free_area_init_node() is only used by x86 to initialize a memory-less nodes. Make its name reflect this and drop all the function parameters except node ID as they are anyway zero. Signed-off-by:
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Mike Rapoport authored
Some architectures (e.g. ARC) have the ZONE_HIGHMEM zone below the ZONE_NORMAL. Allowing free_area_init() parse max_zone_pfn array even it is sorted in descending order allows using free_area_init() on such architectures. Add top -> down traversal of max_zone_pfn array in free_area_init() and use the latter in ARC node/zone initialization. [rppt@kernel.org: ARC fix] Link: http://lkml.kernel.org/r/20200504153901.GM14260@kernel.org [rppt@linux.ibm.com: arc: free_area_init(): take into account PAE40 mode] Link: http://lkml.kernel.org/r/20200507205900.GH683243@linux.ibm.com [akpm@linux-foundation.org: declare arch_has_descending_max_zone_pfns()] Signed-off-by:
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Mike Rapoport authored
The memmap_init() function was made to iterate over memblock regions and as the result the early_pfn_in_nid() function became obsolete. Since CONFIG_NODES_SPAN_OTHER_NODES is only used to pick a stub or a real implementation of early_pfn_in_nid(), it is also not needed anymore. Remove both early_pfn_in_nid() and the CONFIG_NODES_SPAN_OTHER_NODES. Co-developed-by:
Hoan Tran <Hoan@os.amperecomputing.com> Signed-off-by:
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Baoquan He authored
When called during boot the memmap_init_zone() function checks if each PFN is valid and actually belongs to the node being initialized using early_pfn_valid() and early_pfn_in_nid(). Each such check may cost up to O(log(n)) where n is the number of memory banks, so for large amount of memory overall time spent in early_pfn*() becomes substantial. Since the information is anyway present in memblock, we can iterate over memblock memory regions in memmap_init() and only call memmap_init_zone() for PFN ranges that are know to be valid and in the appropriate node. [cai@lca.pw: fix a compilation warning from Clang] Link: http://lkml.kernel.org/r/CF6E407F-17DC-427C-8203-21979FB882EF@lca.pw [bhe@redhat.com: fix the incorrect hole in fast_isolate_freepages()] Link: http://lkml.kernel.org/r/8C537EB7-85EE-4DCF-943E-3CC0ED0DF56D@lca.pw Link: http://lkml.kernel.org/r/20200521014407.29690-1-bhe@redhat.comSigned-off-by:
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Mike Rapoport authored
free_area_init() only requires the definition of maximal PFN for each of the supported zone rater than calculation of actual zone sizes and the sizes of the holes between the zones. After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP the free_area_init() is available to all architectures. Using this function instead of free_area_init_node() simplifies the zone detection. Signed-off-by:
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Mike Rapoport authored
free_area_init() only requires the definition of maximal PFN for each of the supported zone rater than calculation of actual zone sizes and the sizes of the holes between the zones. After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP the free_area_init() is available to all architectures. Using this function instead of free_area_init_node() simplifies the zone detection. Signed-off-by:
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Mike Rapoport authored
free_area_init() only requires the definition of maximal PFN for each of the supported zone rater than calculation of actual zone sizes and the sizes of the holes between the zones. After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP the free_area_init() is available to all architectures. Using this function instead of free_area_init_node() simplifies the zone detection. Signed-off-by:
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Mike Rapoport authored
free_area_init() only requires the definition of maximal PFN for each of the supported zone rater than calculation of actual zone sizes and the sizes of the holes between the zones. After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP the free_area_init() is available to all architectures. Using this function instead of free_area_init_node() simplifies the zone detection. Signed-off-by:
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Mike Rapoport authored
free_area_init() only requires the definition of maximal PFN for each of the supported zone rater than calculation of actual zone sizes and the sizes of the holes between the zones. After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP the free_area_init() is available to all architectures. Using this function instead of free_area_init_node() simplifies the zone detection. Signed-off-by:
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Mike Rapoport authored
The free_area_init() function only requires the definition of maximal PFN for each of the supported zone rater than calculation of actual zone sizes and the sizes of the holes between the zones. After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP the free_area_init() is available to all architectures. Using this function instead of free_area_init_node() simplifies the zone detection. Signed-off-by:
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Mike Rapoport authored
The free_area_init() function only requires the definition of maximal PFN for each of the supported zone rater than calculation of actual zone sizes and the sizes of the holes between the zones. After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP the free_area_init() is available to all architectures. Using this function instead of free_area_init_node() simplifies the zone detection. Signed-off-by:
Catalin Marinas <catalin.marinas@arm.com> Cc: Baoquan He <bhe@redhat.com> Cc: Brian Cain <bcain@codeaurora.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Ungerer <gerg@linux-m68k.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Simek <monstr@monstr.eu> Cc: Nick Hu <nickhu@andestech.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Link: http://lkml.kernel.org/r/20200412194859.12663-9-rppt@kernel.orgSigned-off-by:
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Mike Rapoport authored
free_area_init() only requires the definition of maximal PFN for each of the supported zone rater than calculation of actual zone sizes and the sizes of the holes between the zones. After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP the free_area_init() is available to all architectures. Using this function instead of free_area_init_node() simplifies the zone detection. Signed-off-by:
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Mike Rapoport authored
free_area_init() only requires the definition of maximal PFN for each of the supported zone rater than calculation of actual zone sizes and the sizes of the holes between the zones. After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP the free_area_init() is available to all architectures. Using this function instead of free_area_init_node() simplifies the zone detection. Signed-off-by:
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Mike Rapoport authored
free_area_init() has effectively became a wrapper for free_area_init_nodes() and there is no point of keeping it. Still free_area_init() name is shorter and more general as it does not imply necessity to initialize multiple nodes. Rename free_area_init_nodes() to free_area_init(), update the callers and drop old version of free_area_init(). Signed-off-by:
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Mike Rapoport authored
Currently, architectures that use free_area_init() to initialize memory map and node and zone structures need to calculate zone and hole sizes. We can use free_area_init_nodes() instead and let it detect the zone boundaries while the architectures will only have to supply the possible limits for the zones. Signed-off-by:
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Mike Rapoport authored
CONFIG_HAVE_MEMBLOCK_NODE_MAP is used to differentiate initialization of nodes and zones structures between the systems that have region to node mapping in memblock and those that don't. Currently all the NUMA architectures enable this option and for the non-NUMA systems we can presume that all the memory belongs to node 0 and therefore the compile time configuration option is not required. The remaining few architectures that use DISCONTIGMEM without NUMA are easily updated to use memblock_add_node() instead of memblock_add() and thus have proper correspondence of memblock regions to NUMA nodes. Still, free_area_init_node() must have a backward compatible version because its semantics with and without CONFIG_HAVE_MEMBLOCK_NODE_MAP is different. Once all the architectures will use the new semantics, the entire compatibility layer can be dropped. To avoid addition of extra run time memory to store node id for architectures that keep memblock but have only a single node, the node id field of the memblock_region is guarded by CONFIG_NEED_MULTIPLE_NODES and the corresponding accessors presume that in those cases it is always 0. Signed-off-by:
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Mike Rapoport authored
early_pfn_to_nid() and its helper __early_pfn_to_nid() are spread around include/linux/mm.h, include/linux/mmzone.h and mm/page_alloc.c. Drop unused stub for __early_pfn_to_nid() and move its actual generic implementation close to its users. Signed-off-by:
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Mike Rapoport authored
Patch series "mm: rework free_area_init*() funcitons". After the discussion [1] about removal of CONFIG_NODES_SPAN_OTHER_NODES and CONFIG_HAVE_MEMBLOCK_NODE_MAP options, I took it a bit further and updated the node/zone initialization. Since all architectures have memblock, it is possible to use only the newer version of free_area_init_node() that calculates the zone and node boundaries based on memblock node mapping and architectural limits on possible zone PFNs. The architectures that still determined zone and hole sizes can be switched to the generic code and the old code that took those zone and hole sizes can be simply removed. And, since it all started from the removal of CONFIG_NODES_SPAN_OTHER_NODES, the memmap_init() is now updated to iterate over memblocks and so it does not need to perform early_pfn_to_nid() query for every PFN. [1] https://lore.kernel.org/lkml/1585420282-25630-1-git-send-email-Hoan@os.amperecomputing.com This patch (of 21): There are several places in the code that directly dereference memblock_region.nid despite this field being defined only when CONFIG_HAVE_MEMBLOCK_NODE_MAP=y. Replace these with calls to memblock_get_region_nid() to improve code robustness and to avoid possible breakage when CONFIG_HAVE_MEMBLOCK_NODE_MAP will be removed. Signed-off-by:
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Michal Hocko authored
It seems that the existing documentation is not explicit about the expected usage and potential risks enough. While it is calls out that users have to free memory when using this flag it is not really apparent that users have to careful to not deplete memory reserves and that they should implement some sort of throttling wrt. freeing process. This is partly based on Neil's explanation [1]. Let's also call out that a pre allocated pool allocator should be considered. [1] http://lkml.kernel.org/r/877dz0yxoa.fsf@notabene.neil.brown.name [akpm@linux-foundation.org: coding style fixes] [mhocko@kernel.org: update] Link: http://lkml.kernel.org/r/20200406070137.GC19426@dhcp22.suse.czSigned-off-by:
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Daniel Axtens authored
The memcmp KASAN self-test fails on a kernel with both KASAN and FORTIFY_SOURCE. When FORTIFY_SOURCE is on, a number of functions are replaced with fortified versions, which attempt to check the sizes of the operands. However, these functions often directly invoke __builtin_foo() once they have performed the fortify check. Using __builtins may bypass KASAN checks if the compiler decides to inline it's own implementation as sequence of instructions, rather than emit a function call that goes out to a KASAN-instrumented implementation. Why is only memcmp affected? ============================ Of the string and string-like functions that kasan_test tests, only memcmp is replaced by an inline sequence of instructions in my testing on x86 with gcc version 9.2.1 20191008 (Ubuntu 9.2.1-9ubuntu2). I believe this is due to compiler heuristics. For example, if I annotate kmalloc calls with the alloc_size annotation (and disable some fortify compile-time checking!), the compiler will replace every memset except the one in kmalloc_uaf_memset with inline instructions. (I have some WIP patches to add this annotation.) Does this affect other functions in string.h? ============================================= Yes. Anything that uses __builtin_* rather than __real_* could be affected. This looks like: - strncpy - strcat - strlen - strlcpy maybe, under some circumstances? - strncat under some circumstances - memset - memcpy - memmove - memcmp (as noted) - memchr - strcpy Whether a function call is emitted always depends on the compiler. Most bugs should get caught by FORTIFY_SOURCE, but the missed memcmp test shows that this is not always the case. Isn't FORTIFY_SOURCE disabled with KASAN? ========================================- The string headers on all arches supporting KASAN disable fortify with kasan, but only when address sanitisation is _also_ disabled. For example from x86: #if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__) /* * For files that are not instrumented (e.g. mm/slub.c) we * should use not instrumented version of mem* functions. */ #define memcpy(dst, src, len) __memcpy(dst, src, len) #define memmove(dst, src, len) __memmove(dst, src, len) #define memset(s, c, n) __memset(s, c, n) #ifndef __NO_FORTIFY #define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */ #endif #endif This comes from commit 6974f0c4 ("include/linux/string.h: add the option of fortified string.h functions"), and doesn't work when KASAN is enabled and the file is supposed to be sanitised - as with test_kasan.c I'm pretty sure this is not wrong, but not as expansive it should be: * we shouldn't use __builtin_memcpy etc in files where we don't have instrumentation - it could devolve into a function call to memcpy, which will be instrumented. Rather, we should use __memcpy which by convention is not instrumented. * we also shouldn't be using __builtin_memcpy when we have a KASAN instrumented file, because it could be replaced with inline asm that will not be instrumented. What is correct behaviour? ========================== Firstly, there is some overlap between fortification and KASAN: both provide some level of _runtime_ checking. Only fortify provides compile-time checking. KASAN and fortify can pick up different things at runtime: - Some fortify functions, notably the string functions, could easily be modified to consider sub-object sizes (e.g. members within a struct), and I have some WIP patches to do this. KASAN cannot detect these because it cannot insert poision between members of a struct. - KASAN can detect many over-reads/over-writes when the sizes of both operands are unknown, which fortify cannot. So there are a couple of options: 1) Flip the test: disable fortify in santised files and enable it in unsanitised files. This at least stops us missing KASAN checking, but we lose the fortify checking. 2) Make the fortify code always call out to real versions. Do this only for KASAN, for fear of losing the inlining opportunities we get from __builtin_*. (We can't use kasan_check_{read,write}: because the fortify functions are _extern inline_, you can't include _static_ inline functions without a compiler warning. kasan_check_{read,write} are static inline so we can't use them even when they would otherwise be suitable.) Take approach 2 and call out to real versions when KASAN is enabled. Use __underlying_foo to distinguish from __real_foo: __real_foo always refers to the kernel's implementation of foo, __underlying_foo could be either the kernel implementation or the __builtin_foo implementation. This is sometimes enough to make the memcmp test succeed with FORTIFY_SOURCE enabled. It is at least enough to get the function call into the module. One more fix is needed to make it reliable: see the next patch. Fixes: 6974f0c4 ("include/linux/string.h: add the option of fortified string.h functions") Signed-off-by:
Daniel Axtens <dja@axtens.net> Signed-off-by:
David Gow <davidgow@google.com> Reviewed-by:
Dmitry Vyukov <dvyukov@google.com> Cc: Daniel Micay <danielmicay@gmail.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Link: http://lkml.kernel.org/r/20200423154503.5103-3-dja@axtens.netSigned-off-by:
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Daniel Axtens authored
Patch series "Fix some incompatibilites between KASAN and FORTIFY_SOURCE", v4. 3 KASAN self-tests fail on a kernel with both KASAN and FORTIFY_SOURCE: memchr, memcmp and strlen. When FORTIFY_SOURCE is on, a number of functions are replaced with fortified versions, which attempt to check the sizes of the operands. However, these functions often directly invoke __builtin_foo() once they have performed the fortify check. The compiler can detect that the results of these functions are not used, and knows that they have no other side effects, and so can eliminate them as dead code. Why are only memchr, memcmp and strlen affected? ================================================ Of string and string-like functions, kasan_test tests: * strchr -> not affected, no fortified version * strrchr -> likewise * strcmp -> likewise * strncmp -> likewise * strnlen -> not affected, the fortify source implementation calls the underlying strnlen implementation which is instrumented, not a builtin * strlen -> affected, the fortify souce implementation calls a __builtin version which the compiler can determine is dead. * memchr -> likewise * memcmp -> likewise * memset -> not affected, the compiler knows that memset writes to its first argument and therefore is not dead. Why does this not affect the functions normally? ================================================ In string.h, these functions are not marked as __pure, so the compiler cannot know that they do not have side effects. If relevant functions are marked as __pure in string.h, we see the following warnings and the functions are elided: lib/test_kasan.c: In function `kasan_memchr': lib/test_kasan.c:606:2: warning: statement with no effect [-Wunused-value] memchr(ptr, '1', size + 1); ^~~~~~~~~~~~~~~~~~~~~~~~~~ lib/test_kasan.c: In function `kasan_memcmp': lib/test_kasan.c:622:2: warning: statement with no effect [-Wunused-value] memcmp(ptr, arr, size+1); ^~~~~~~~~~~~~~~~~~~~~~~~ lib/test_kasan.c: In function `kasan_strings': lib/test_kasan.c:645:2: warning: statement with no effect [-Wunused-value] strchr(ptr, '1'); ^~~~~~~~~~~~~~~~ ... This annotation would make sense to add and could be added at any point, so the behaviour of test_kasan.c should change. The fix ======= Make all the functions that are pure write their results to a global, which makes them live. The strlen and memchr tests now pass. The memcmp test still fails to trigger, which is addressed in the next patch. [dja@axtens.net: drop patch 3] Link: http://lkml.kernel.org/r/20200424145521.8203-2-dja@axtens.net Fixes: 0c96350a ("lib/test_kasan.c: add tests for several string/memory API functions") Signed-off-by:
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