linux/mm/vmalloc.c, branch v5.3

mm/vmalloc.c: fix percpu free VM area search criteria

2019-08-13T23:06:52Z

Recent changes to the vmalloc code by commit 68ad4a330433 ("mm/vmalloc.c: keep track of free blocks for vmap allocation") can cause spurious percpu allocation failures. These, in turn, can result in panic()s in the slub code. One such possible panic was reported by Dave Hansen in following link https://lkml.org/lkml/2019/6/19/939. Another related panic observed is, RIP: 0033:0x7f46f7441b9b Call Trace: dump_stack+0x61/0x80 pcpu_alloc.cold.30+0x22/0x4f mem_cgroup_css_alloc+0x110/0x650 cgroup_apply_control_enable+0x133/0x330 cgroup_mkdir+0x41b/0x500 kernfs_iop_mkdir+0x5a/0x90 vfs_mkdir+0x102/0x1b0 do_mkdirat+0x7d/0xf0 do_syscall_64+0x5b/0x180 entry_SYSCALL_64_after_hwframe+0x44/0xa9 VMALLOC memory manager divides the entire VMALLOC space (VMALLOC_START to VMALLOC_END) into multiple VM areas (struct vm_areas), and it mainly uses two lists (vmap_area_list & free_vmap_area_list) to track the used and free VM areas in VMALLOC space. And pcpu_get_vm_areas(offsets[], sizes[], nr_vms, align) function is used for allocating congruent VM areas for percpu memory allocator. In order to not conflict with VMALLOC users, pcpu_get_vm_areas allocates VM areas near the end of the VMALLOC space. So the search for free vm_area for the given requirement starts near VMALLOC_END and moves upwards towards VMALLOC_START. Prior to commit 68ad4a330433, the search for free vm_area in pcpu_get_vm_areas() involves following two main steps. Step 1: Find a aligned "base" adress near VMALLOC_END. va = free vm area near VMALLOC_END Step 2: Loop through number of requested vm_areas and check, Step 2.1: if (base < VMALLOC_START) 1. fail with error Step 2.2: // end is offsets[area] + sizes[area] if (base + end > va->vm_end) 1. Move the base downwards and repeat Step 2 Step 2.3: if (base + start < va->vm_start) 1. Move to previous free vm_area node, find aligned base address and repeat Step 2 But Commit 68ad4a330433 removed Step 2.2 and modified Step 2.3 as below: Step 2.3: if (base + start < va->vm_start || base + end > va->vm_end) 1. Move to previous free vm_area node, find aligned base address and repeat Step 2 Above change is the root cause of spurious percpu memory allocation failures. For example, consider a case where a relatively large vm_area (~ 30 TB) was ignored in free vm_area search because it did not pass the base + end < vm->vm_end boundary check. Ignoring such large free vm_area's would lead to not finding free vm_area within boundary of VMALLOC_start to VMALLOC_END which in turn leads to allocation failures. So modify the search algorithm to include Step 2.2. Link: http://lkml.kernel.org/r/20190729232139.91131-1-sathyanarayanan.kuppuswamy@linux.intel.com Fixes: 68ad4a330433 ("mm/vmalloc.c: keep track of free blocks for vmap allocation") Signed-off-by: Kuppuswamy Sathyanarayanan Reported-by: Dave Hansen Acked-by: Dennis Zhou Reviewed-by: Uladzislau Rezki (Sony) Cc: Roman Gushchin Cc: sathyanarayanan kuppuswamy Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()

2019-07-22T08:18:30Z

On x86-32 with PTI enabled, parts of the kernel page-tables are not shared between processes. This can cause mappings in the vmalloc/ioremap area to persist in some page-tables after the region is unmapped and released. When the region is re-used the processes with the old mappings do not fault in the new mappings but still access the old ones. This causes undefined behavior, in reality often data corruption, kernel oopses and panics and even spontaneous reboots. Fix this problem by activly syncing unmaps in the vmalloc/ioremap area to all page-tables in the system before the regions can be re-used. References: https://bugzilla.suse.com/show_bug.cgi?id=1118689 Fixes: 5d72b4fba40ef ('x86, mm: support huge I/O mapping capability I/F') Signed-off-by: Joerg Roedel Signed-off-by: Thomas Gleixner Reviewed-by: Dave Hansen Link: https://lkml.kernel.org/r/20190719184652.11391-4-joro@8bytes.org

mm: vmalloc: show number of vmalloc pages in /proc/meminfo

2019-07-12T18:05:47Z

Vmalloc() is getting more and more used these days (kernel stacks, bpf and percpu allocator are new top users), and the total % of memory consumed by vmalloc() can be pretty significant and changes dynamically. /proc/meminfo is the best place to display this information: its top goal is to show top consumers of the memory. Since the VmallocUsed field in /proc/meminfo is not in use for quite a long time (it has been defined to 0 by a5ad88ce8c7f ("mm: get rid of 'vmalloc_info' from /proc/meminfo")), let's reuse it for showing the actual physical memory consumption of vmalloc(). Link: http://lkml.kernel.org/r/20190417194002.12369-3-guro@fb.com Signed-off-by: Roman Gushchin Acked-by: Johannes Weiner Acked-by: Vlastimil Babka Reviewed-by: Andrew Morton Cc: Matthew Wilcox Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/vmalloc.c: spelling> s/informaion/information/

2019-07-12T18:05:46Z

Link: http://lkml.kernel.org/r/20190607113509.15032-1-geert+renesas@glider.be Signed-off-by: Geert Uytterhoeven Reviewed-by: Andrew Morton Acked-by: Souptick Joarder Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/vmalloc.c: switch to WARN_ON() and move it under unlink_va()

2019-07-12T18:05:46Z

Trigger a warning if an object that is about to be freed is detached. We used to have a BUG_ON(), but even though it is considered as faulty behaviour that is not a good reason to break a system. Link: http://lkml.kernel.org/r/20190606120411.8298-5-urezki@gmail.com Signed-off-by: Uladzislau Rezki (Sony) Cc: Roman Gushchin Cc: Hillf Danton Cc: Michal Hocko Cc: Matthew Wilcox Cc: Oleksiy Avramchenko Cc: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/vmalloc.c: get rid of one single unlink_va() when merge

2019-07-12T18:05:46Z

It does not make sense to try to "unlink" the node that is definitely not linked with a list nor tree. On the first merge step VA just points to the previously disconnected busy area. On the second step, check if the node has been merged and do "unlink" if so, because now it points to an object that must be linked. Link: http://lkml.kernel.org/r/20190606120411.8298-4-urezki@gmail.com Signed-off-by: Uladzislau Rezki (Sony) Acked-by: Hillf Danton Reviewed-by: Roman Gushchin Cc: Matthew Wilcox Cc: Michal Hocko Cc: Oleksiy Avramchenko Cc: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/vmalloc.c: preload a CPU with one object for split purpose

2019-07-12T18:05:46Z

Refactor the NE_FIT_TYPE split case when it comes to an allocation of one extra object. We need it in order to build a remaining space. The preload is done per CPU in non-atomic context with GFP_KERNEL flags. More permissive parameters can be beneficial for systems which are suffer from high memory pressure or low memory condition. For example on my KVM system(4xCPUs, no swap, 256MB RAM) i can simulate the failure of page allocation with GFP_NOWAIT flags. Using "stress-ng" tool and starting N workers spinning on fork() and exit(), i can trigger below trace: [ 179.815161] stress-ng-fork: page allocation failure: order:0, mode:0x40800(GFP_NOWAIT|__GFP_COMP), nodemask=(null),cpuset=/,mems_allowed=0 [ 179.815168] CPU: 0 PID: 12612 Comm: stress-ng-fork Not tainted 5.2.0-rc3+ #1003 [ 179.815170] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 179.815171] Call Trace: [ 179.815178] dump_stack+0x5c/0x7b [ 179.815182] warn_alloc+0x108/0x190 [ 179.815187] __alloc_pages_slowpath+0xdc7/0xdf0 [ 179.815191] __alloc_pages_nodemask+0x2de/0x330 [ 179.815194] cache_grow_begin+0x77/0x420 [ 179.815197] fallback_alloc+0x161/0x200 [ 179.815200] kmem_cache_alloc+0x1c9/0x570 [ 179.815202] alloc_vmap_area+0x32c/0x990 [ 179.815206] __get_vm_area_node+0xb0/0x170 [ 179.815208] __vmalloc_node_range+0x6d/0x230 [ 179.815211] ? _do_fork+0xce/0x3d0 [ 179.815213] copy_process.part.46+0x850/0x1b90 [ 179.815215] ? _do_fork+0xce/0x3d0 [ 179.815219] _do_fork+0xce/0x3d0 [ 179.815226] ? __do_page_fault+0x2bf/0x4e0 [ 179.815229] do_syscall_64+0x55/0x130 [ 179.815231] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 179.815234] RIP: 0033:0x7fedec4c738b ... [ 179.815237] RSP: 002b:00007ffda469d730 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 [ 179.815239] RAX: ffffffffffffffda RBX: 00007ffda469d730 RCX: 00007fedec4c738b [ 179.815240] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 [ 179.815241] RBP: 00007ffda469d780 R08: 00007fededd6e300 R09: 00007ffda47f50a0 [ 179.815242] R10: 00007fededd6e5d0 R11: 0000000000000246 R12: 0000000000000000 [ 179.815243] R13: 0000000000000020 R14: 0000000000000000 R15: 0000000000000000 [ 179.815245] Mem-Info: [ 179.815249] active_anon:12686 inactive_anon:14760 isolated_anon:0 active_file:502 inactive_file:61 isolated_file:70 unevictable:2 dirty:0 writeback:0 unstable:0 slab_reclaimable:2380 slab_unreclaimable:7520 mapped:15069 shmem:14813 pagetables:10833 bounce:0 free:1922 free_pcp:229 free_cma:0 Link: http://lkml.kernel.org/r/20190606120411.8298-3-urezki@gmail.com Signed-off-by: Uladzislau Rezki (Sony) Cc: Hillf Danton Cc: Matthew Wilcox Cc: Michal Hocko Cc: Oleksiy Avramchenko Cc: Roman Gushchin Cc: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/vmalloc.c: remove "node" argument

2019-07-12T18:05:46Z

Patch series "Some cleanups for the KVA/vmalloc", v5. This patch (of 4): Remove unused argument from the __alloc_vmap_area() function. Link: http://lkml.kernel.org/r/20190606120411.8298-2-urezki@gmail.com Signed-off-by: Uladzislau Rezki (Sony) Reviewed-by: Andrew Morton Reviewed-by: Roman Gushchin Cc: Hillf Danton Cc: Matthew Wilcox Cc: Michal Hocko Cc: Oleksiy Avramchenko Cc: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/pgtable: drop pgtable_t variable from pte_fn_t functions

2019-07-12T18:05:46Z

Drop the pgtable_t variable from all implementation for pte_fn_t as none of them use it. apply_to_pte_range() should stop computing it as well. Should help us save some cycles. Link: http://lkml.kernel.org/r/1556803126-26596-1-git-send-email-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual Acked-by: Matthew Wilcox Cc: Ard Biesheuvel Cc: Russell King Cc: Catalin Marinas Cc: Will Deacon Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Michal Hocko Cc: Logan Gunthorpe Cc: "Kirill A. Shutemov" Cc: Dan Williams Cc: Cc: Mike Rapoport Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2019-07-08T16:54:55Z

Pull arm64 updates from Catalin Marinas: - arm64 support for syscall emulation via PTRACE_SYSEMU{,_SINGLESTEP} - Wire up VM_FLUSH_RESET_PERMS for arm64, allowing the core code to manage the permissions of executable vmalloc regions more strictly - Slight performance improvement by keeping softirqs enabled while touching the FPSIMD/SVE state (kernel_neon_begin/end) - Expose a couple of ARMv8.5 features to user (HWCAP): CondM (new XAFLAG and AXFLAG instructions for floating point comparison flags manipulation) and FRINT (rounding floating point numbers to integers) - Re-instate ARM64_PSEUDO_NMI support which was previously marked as BROKEN due to some bugs (now fixed) - Improve parking of stopped CPUs and implement an arm64-specific panic_smp_self_stop() to avoid warning on not being able to stop secondary CPUs during panic - perf: enable the ARM Statistical Profiling Extensions (SPE) on ACPI platforms - perf: DDR performance monitor support for iMX8QXP - cache_line_size() can now be set from DT or ACPI/PPTT if provided to cope with a system cache info not exposed via the CPUID registers - Avoid warning on hardware cache line size greater than ARCH_DMA_MINALIGN if the system is fully coherent - arm64 do_page_fault() and hugetlb cleanups - Refactor set_pte_at() to avoid redundant READ_ONCE(*ptep) - Ignore ACPI 5.1 FADTs reported as 5.0 (infer from the 'arm_boot_flags' introduced in 5.1) - CONFIG_RANDOMIZE_BASE now enabled in defconfig - Allow the selection of ARM64_MODULE_PLTS, currently only done via RANDOMIZE_BASE (and an erratum workaround), allowing modules to spill over into the vmalloc area - Make ZONE_DMA32 configurable * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (54 commits) perf: arm_spe: Enable ACPI/Platform automatic module loading arm_pmu: acpi: spe: Add initial MADT/SPE probing ACPI/PPTT: Add function to return ACPI 6.3 Identical tokens ACPI/PPTT: Modify node flag detection to find last IDENTICAL x86/entry: Simplify _TIF_SYSCALL_EMU handling arm64: rename dump_instr as dump_kernel_instr arm64/mm: Drop [PTE|PMD]_TYPE_FAULT arm64: Implement panic_smp_self_stop() arm64: Improve parking of stopped CPUs arm64: Expose FRINT capabilities to userspace arm64: Expose ARMv8.5 CondM capability to userspace arm64: defconfig: enable CONFIG_RANDOMIZE_BASE arm64: ARM64_MODULES_PLTS must depend on MODULES arm64: bpf: do not allocate executable memory arm64/kprobes: set VM_FLUSH_RESET_PERMS on kprobe instruction pages arm64/mm: wire up CONFIG_ARCH_HAS_SET_DIRECT_MAP arm64: module: create module allocations without exec permissions arm64: Allow user selection of ARM64_MODULE_PLTS acpi/arm64: ignore 5.1 FADTs that are reported as 5.0 arm64: Allow selecting Pseudo-NMI again ...