1. 29 Apr, 2013 40 commits
    • Cody P Schafer's avatar
      page_alloc: make setup_nr_node_ids() usable for arch init code · f9872caf
      Cody P Schafer authored
      powerpc and x86 were opencoding copies of setup_nr_node_ids(), which
      page_alloc provides but makes static.  Make it avaliable to the archs in
      linux/mm.h.
      Signed-off-by: default avatarCody P Schafer <cody@linux.vnet.ibm.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f9872caf
    • Russ Anderson's avatar
      mm: speedup in __early_pfn_to_nid · 7c243c71
      Russ Anderson authored
      When booting on a large memory system, the kernel spends considerable
      time in memmap_init_zone() setting up memory zones.  Analysis shows
      significant time spent in __early_pfn_to_nid().
      
      The routine memmap_init_zone() checks each PFN to verify the nid is
      valid.  __early_pfn_to_nid() sequentially scans the list of pfn ranges
      to find the right range and returns the nid.  This does not scale well.
      On a 4 TB (single rack) system there are 308 memory ranges to scan.  The
      higher the PFN the more time spent sequentially spinning through memory
      ranges.
      
      Since memmap_init_zone() increments pfn, it will almost always be
      looking for the same range as the previous pfn, so check that range
      first.  If it is in the same range, return that nid.  If not, scan the
      list as before.
      
      A 4 TB (single rack) UV1 system takes 512 seconds to get through the
      zone code.  This performance optimization reduces the time by 189
      seconds, a 36% improvement.
      
      A 2 TB (single rack) UV2 system goes from 212.7 seconds to 99.8 seconds,
      a 112.9 second (53%) reduction.
      
      [akpm@linux-foundation.org: make the statics __meminitdata]
      [akpm@linux-foundation.org: fix comment formatting]
      [akpm@linux-foundation.org: fix ia64, per yinghai]
      [akpm@linux-foundation.org: add missing semicolon, per Tony]
      Signed-off-by: default avatarRuss Anderson <rja@sgi.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Tested-by: default avatar"Luck, Tony" <tony.luck@intel.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: Lin Feng <linfeng@cn.fujitsu.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7c243c71
    • Jianguo Wu's avatar
    • Mel Gorman's avatar
      mm: page_alloc: avoid marking zones full prematurely after zone_reclaim() · fed2719e
      Mel Gorman authored
      The following problem was reported against a distribution kernel when
      zone_reclaim was enabled but the same problem applies to the mainline
      kernel.  The reproduction case was as follows
      
      1. Run numactl -m +0 dd if=largefile of=/dev/null
         This allocates a large number of clean pages in node 0
      
      2. numactl -N +0 memhog 0.5*Mg
         This start a memory-using application in node 0.
      
      The expected behaviour is that the clean pages get reclaimed and the
      application uses node 0 for its memory.  The observed behaviour was that
      the memory for the memhog application was allocated off-node since
      commits cd38b115 ("mm: page allocator: initialise ZLC for first zone
      eligible for zone_reclaim") and commit 76d3fbf8 ("mm: page
      allocator: reconsider zones for allocation after direct reclaim").
      
      The assumption of those patches was that it was always preferable to
      allocate quickly than stall for long periods of time and they were meant
      to take care that the zone was only marked full when necessary but an
      important case was missed.
      
      In the allocator fast path, only the low watermarks are checked.  If the
      zones free pages are between the low and min watermark then allocations
      from the allocators slow path will succeed.  However, zone_reclaim will
      only reclaim SWAP_CLUSTER_MAX or 1<<order pages.  There is no guarantee
      that this will meet the low watermark causing the zone to be marked full
      prematurely.
      
      This patch will only mark the zone full after zone_reclaim if it the min
      watermarks are checked or if page reclaim failed to make sufficient
      progress.
      
      [mhocko@suse.cz: fix alloc_flags test]
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Reported-by: default avatarHedi Berriche <hedi@sgi.com>
      Tested-by: default avatarHedi Berriche <hedi@sgi.com>
      Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
      Reviewed-by: default avatarWanpeng Li <liwanp@linux.vnet.ibm.com>
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      fed2719e
    • Johannes Weiner's avatar
      x86-64: fall back to regular page vmemmap on allocation failure · 8e2cdbcb
      Johannes Weiner authored
      Memory hotplug can happen on a machine under load, memory shortness
      and fragmentation, so huge page allocations for the vmemmap are not
      guaranteed to succeed.
      
      Try to fall back to regular pages before failing the hotplug event
      completely.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: Ben Hutchings <ben@decadent.org.uk>
      Cc: Bernhard Schmidt <Bernhard.Schmidt@lrz.de>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Russell King <rmk@arm.linux.org.uk>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: "Luck, Tony" <tony.luck@intel.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: David Miller <davem@davemloft.net>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      8e2cdbcb
    • Johannes Weiner's avatar
      x86-64: use vmemmap_populate_basepages() for !pse setups · e8216da5
      Johannes Weiner authored
      We already have generic code to allocate vmemmap with regular pages, use
      it.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: Ben Hutchings <ben@decadent.org.uk>
      Cc: Bernhard Schmidt <Bernhard.Schmidt@lrz.de>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Russell King <rmk@arm.linux.org.uk>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: "Luck, Tony" <tony.luck@intel.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: David Miller <davem@davemloft.net>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e8216da5
    • Johannes Weiner's avatar
      x86-64: remove dead debugging code for !pse setups · 6c7a2ca4
      Johannes Weiner authored
      No need to maintain addr_end and p_end when they are never actually read
      anywhere on !pse setups.  Remove the dead code.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: Ben Hutchings <ben@decadent.org.uk>
      Cc: Bernhard Schmidt <Bernhard.Schmidt@lrz.de>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Russell King <rmk@arm.linux.org.uk>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: "Luck, Tony" <tony.luck@intel.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: David Miller <davem@davemloft.net>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6c7a2ca4
    • Johannes Weiner's avatar
      sparse-vmemmap: specify vmemmap population range in bytes · 0aad818b
      Johannes Weiner authored
      The sparse code, when asking the architecture to populate the vmemmap,
      specifies the section range as a starting page and a number of pages.
      
      This is an awkward interface, because none of the arch-specific code
      actually thinks of the range in terms of 'struct page' units and always
      translates it to bytes first.
      
      In addition, later patches mix huge page and regular page backing for
      the vmemmap.  For this, they need to call vmemmap_populate_basepages()
      on sub-section ranges with PAGE_SIZE and PMD_SIZE in mind.  But these
      are not necessarily multiples of the 'struct page' size and so this unit
      is too coarse.
      
      Just translate the section range into bytes once in the generic sparse
      code, then pass byte ranges down the stack.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: Ben Hutchings <ben@decadent.org.uk>
      Cc: Bernhard Schmidt <Bernhard.Schmidt@lrz.de>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Russell King <rmk@arm.linux.org.uk>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: "Luck, Tony" <tony.luck@intel.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
      Tested-by: default avatarDavid S. Miller <davem@davemloft.net>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0aad818b
    • Ben Hutchings's avatar
      mm: try harder to allocate vmemmap blocks · 055e4fd9
      Ben Hutchings authored
      Hot-adding memory on x86_64 normally requires huge page allocation.
      When this is done to a VM guest, it's usually because the system is
      already tight on memory, so the request tends to fail.  Try to avoid
      this by adding __GFP_REPEAT to the allocation flags.
      
      Addresses http://bugs.debian.org/699913Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reported-by: default avatarBernhard Schmidt <Bernhard.Schmidt@lrz.de>
      Tested-by: default avatarBernhard Schmidt <Bernhard.Schmidt@lrz.de>
      Cc: Russell King <rmk@arm.linux.org.uk>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: "Luck, Tony" <tony.luck@intel.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: David Miller <davem@davemloft.net>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      055e4fd9
    • David Rientjes's avatar
      mm, hugetlb: include hugepages in meminfo · 949f7ec5
      David Rientjes authored
      Particularly in oom conditions, it's troublesome that hugetlb memory is
      not displayed.  All other meminfo that is emitted will not add up to
      what is expected, and there is no artifact left in the kernel log to
      show that a potentially significant amount of memory is actually
      allocated as hugepages which are not available to be reclaimed.
      
      Booting with hugepages=8192 on the command line, this memory is now
      shown in oom conditions.  For example, with echo m >
      /proc/sysrq-trigger:
      
        Node 0 hugepages_total=2048 hugepages_free=2048 hugepages_surp=0 hugepages_size=2048kB
        Node 1 hugepages_total=2048 hugepages_free=2048 hugepages_surp=0 hugepages_size=2048kB
        Node 2 hugepages_total=2048 hugepages_free=2048 hugepages_surp=0 hugepages_size=2048kB
        Node 3 hugepages_total=2048 hugepages_free=2048 hugepages_surp=0 hugepages_size=2048kB
      
      [akpm@linux-foundation.org: coding-style fixes]
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      949f7ec5
    • Hampson, Steven T's avatar
      mm: merging memory blocks resets mempolicy · 1444f92c
      Hampson, Steven T authored
      Using mbind to change the mempolicy to MPOL_BIND on several adjacent
      mmapped blocks may result in a reset of the mempolicy to MPOL_DEFAULT in
      vma_adjust.
      
      Test code.  Correct result is three lines containing "OK".
      
      #include <stdio.h>
      #include <unistd.h>
      #include <sys/mman.h>
      #include <numaif.h>
      #include <errno.h>
      
      /* gcc mbind_test.c -lnuma -o mbind_test -Wall */
      #define MAXNODE 4096
      
      void allocate()
      {
      	int ret;
      	int len;
      	int policy = -1;
      	unsigned char *p;
      	unsigned long mask[MAXNODE] = { 0 };
      	unsigned long retmask[MAXNODE] = { 0 };
      
      	len = getpagesize() * 0x2fc00;
      	p = mmap(NULL, len, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
      		 -1, 0);
      	if (p == MAP_FAILED)
      		printf("mbind err: %d\n", errno);
      
      	mask[0] = 1;
      	ret = mbind(p, len, MPOL_BIND, mask, MAXNODE, 0);
      	if (ret < 0)
      		printf("mbind err: %d %d\n", ret, errno);
      	ret = get_mempolicy(&policy, retmask, MAXNODE, p, MPOL_F_ADDR);
      	if (ret < 0)
      		printf("get_mempolicy err: %d %d\n", ret, errno);
      
      	if (policy == MPOL_BIND)
      		printf("OK\n");
      	else
      		printf("ERROR: policy is %d\n", policy);
      }
      
      int main()
      {
      	allocate();
      	allocate();
      	allocate();
      	return 0;
      }
      Signed-off-by: default avatarSteven T Hampson <steven.t.hampson@intel.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1444f92c
    • Catalin Marinas's avatar
      arm: set the page table freeing ceiling to TASK_SIZE · 104ad3b3
      Catalin Marinas authored
      ARM processors with LPAE enabled use 3 levels of page tables, with an
      entry in the top level (pgd) covering 1GB of virtual space.  Because of
      the branch relocation limitations on ARM, the loadable modules are
      mapped 16MB below PAGE_OFFSET, making the corresponding 1GB pgd shared
      between kernel modules and user space.
      
      If free_pgtables() is called with the default ceiling 0,
      free_pgd_range() (and subsequently called functions) also frees the page
      table shared between user space and kernel modules (which is normally
      handled by the ARM-specific pgd_free() function).  This patch changes
      defines the ARM USER_PGTABLES_CEILING to TASK_SIZE when CONFIG_ARM_LPAE
      is enabled.
      
      Note that the pgd_free() function already checks the presence of the
      shared pmd page allocated by pgd_alloc() and frees it, though with
      ceiling 0 this wasn't necessary.
      Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
      Cc: Russell King <linux@arm.linux.org.uk>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: <stable@vger.kernel.org>	[3.3+]
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      104ad3b3
    • Hugh Dickins's avatar
      mm: allow arch code to control the user page table ceiling · 6ee8630e
      Hugh Dickins authored
      On architectures where a pgd entry may be shared between user and kernel
      (e.g.  ARM+LPAE), freeing page tables needs a ceiling other than 0.
      This patch introduces a generic USER_PGTABLES_CEILING that arch code can
      override.  It is the responsibility of the arch code setting the ceiling
      to ensure the complete freeing of the page tables (usually in
      pgd_free()).
      
      [catalin.marinas@arm.com: commit log; shift_arg_pages(), asm-generic/pgtables.h changes]
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
      Cc: Russell King <linux@arm.linux.org.uk>
      Cc: <stable@vger.kernel.org>	[3.3+]
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6ee8630e
    • Michal Hocko's avatar
      memcg: do not check for do_swap_account in mem_cgroup_{read,write,reset} · acb6d558
      Michal Hocko authored
      Since commit 2d11085e ("memcg: do not create memsw files if swap
      accounting is disabled") memsw files are created only if memcg swap
      accounting is enabled so it doesn't make any sense to check for it
      explicitly in mem_cgroup_read(), mem_cgroup_write() and
      mem_cgroup_reset().
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Tejun Heo <tj@kernel.org>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      acb6d558
    • Zhang Yanfei's avatar
      mmap: find_vma: remove the WARN_ON_ONCE(!mm) check · ee5df057
      Zhang Yanfei authored
      Remove the WARN_ON_ONCE(!mm) check as the comment suggested.  Kernel
      code calls find_vma only when it is absolutely sure that the mm_struct
      arg to it is non-NULL.
      Signed-off-by: default avatarZhang Yanfei <zhangyanfei@cn.fujitsu.com>
      Cc: k80c <k80ck80c@gmail.com>
      Cc: Michel Lespinasse <walken@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ee5df057
    • Atsushi Kumagai's avatar
      kexec, vmalloc: export additional vmalloc layer information · 13ba3fcb
      Atsushi Kumagai authored
      Now, vmap_area_list is exported as VMCOREINFO for makedumpfile to get
      the start address of vmalloc region (vmalloc_start).  The address which
      contains vmalloc_start value is represented as below:
      
        vmap_area_list.next - OFFSET(vmap_area.list) + OFFSET(vmap_area.va_start)
      
      However, both OFFSET(vmap_area.va_start) and OFFSET(vmap_area.list)
      aren't exported as VMCOREINFO.
      
      So this patch exports them externally with small cleanup.
      
      [akpm@linux-foundation.org: vmalloc.h should include list.h for list_head]
      Signed-off-by: default avatarAtsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
      Cc: Joonsoo Kim <js1304@gmail.com>
      Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Dave Anderson <anderson@redhat.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      13ba3fcb
    • Joonsoo Kim's avatar
      mm, vmalloc: remove list management of vmlist after initializing vmalloc · 4341fa45
      Joonsoo Kim authored
      Now, there is no need to maintain vmlist after initializing vmalloc.  So
      remove related code and data structure.
      Signed-off-by: default avatarJoonsoo Kim <js1304@gmail.com>
      Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Dave Anderson <anderson@redhat.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      4341fa45
    • Joonsoo Kim's avatar
      mm, vmalloc: export vmap_area_list, instead of vmlist · f1c4069e
      Joonsoo Kim authored
      Although our intention is to unexport internal structure entirely, but
      there is one exception for kexec.  kexec dumps address of vmlist and
      makedumpfile uses this information.
      
      We are about to remove vmlist, then another way to retrieve information
      of vmalloc layer is needed for makedumpfile.  For this purpose, we
      export vmap_area_list, instead of vmlist.
      Signed-off-by: default avatarJoonsoo Kim <js1304@gmail.com>
      Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Dave Anderson <anderson@redhat.com>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f1c4069e
    • Joonsoo Kim's avatar
      mm, vmalloc: iterate vmap_area_list, instead of vmlist, in vmallocinfo() · d4033afd
      Joonsoo Kim authored
      This patch is a preparatory step for removing vmlist entirely.  For
      above purpose, we change iterating a vmap_list codes to iterating a
      vmap_area_list.  It is somewhat trivial change, but just one thing
      should be noticed.
      
      Using vmap_area_list in vmallocinfo() introduce ordering problem in SMP
      system.  In s_show(), we retrieve some values from vm_struct.
      vm_struct's values is not fully setup when va->vm is assigned.  Full
      setup is notified by removing VM_UNLIST flag without holding a lock.
      When we see that VM_UNLIST is removed, it is not ensured that vm_struct
      has proper values in view of other CPUs.  So we need smp_[rw]mb for
      ensuring that proper values is assigned when we see that VM_UNLIST is
      removed.
      
      Therefore, this patch not only change a iteration list, but also add a
      appropriate smp_[rw]mb to right places.
      Signed-off-by: default avatarJoonsoo Kim <js1304@gmail.com>
      Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Dave Anderson <anderson@redhat.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d4033afd
    • Joonsoo Kim's avatar
      mm, vmalloc: iterate vmap_area_list in get_vmalloc_info() · f98782dd
      Joonsoo Kim authored
      This patch is a preparatory step for removing vmlist entirely.  For
      above purpose, we change iterating a vmap_list codes to iterating a
      vmap_area_list.  It is somewhat trivial change, but just one thing
      should be noticed.
      
      vmlist is lack of information about some areas in vmalloc address space.
      For example, vm_map_ram() allocate area in vmalloc address space, but it
      doesn't make a link with vmlist.  To provide full information about
      vmalloc address space is better idea, so we don't use va->vm and use
      vmap_area directly.  This makes get_vmalloc_info() more precise.
      Signed-off-by: default avatarJoonsoo Kim <js1304@gmail.com>
      Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Dave Anderson <anderson@redhat.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f98782dd
    • Joonsoo Kim's avatar
      mm, vmalloc: iterate vmap_area_list, instead of vmlist in vread/vwrite() · e81ce85f
      Joonsoo Kim authored
      Now, when we hold a vmap_area_lock, va->vm can't be discarded.  So we can
      safely access to va->vm when iterating a vmap_area_list with holding a
      vmap_area_lock.  With this property, change iterating vmlist codes in
      vread/vwrite() to iterating vmap_area_list.
      
      There is a little difference relate to lock, because vmlist_lock is mutex,
      but, vmap_area_lock is spin_lock.  It may introduce a spinning overhead
      during vread/vwrite() is executing.  But, these are debug-oriented
      functions, so this overhead is not real problem for common case.
      Signed-off-by: default avatarJoonsoo Kim <js1304@gmail.com>
      Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Dave Anderson <anderson@redhat.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e81ce85f
    • Joonsoo Kim's avatar
      mm, vmalloc: protect va->vm by vmap_area_lock · c69480ad
      Joonsoo Kim authored
      Inserting and removing an entry to vmlist is linear time complexity, so
      it is inefficient.  Following patches will try to remove vmlist
      entirely.  This patch is preparing step for it.
      
      For removing vmlist, iterating vmlist codes should be changed to
      iterating a vmap_area_list.  Before implementing that, we should make
      sure that when we iterate a vmap_area_list, accessing to va->vm doesn't
      cause a race condition.  This patch ensure that when iterating a
      vmap_area_list, there is no race condition for accessing to vm_struct.
      Signed-off-by: default avatarJoonsoo Kim <js1304@gmail.com>
      Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Dave Anderson <anderson@redhat.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c69480ad
    • Joonsoo Kim's avatar
      mm, vmalloc: move get_vmalloc_info() to vmalloc.c · db3808c1
      Joonsoo Kim authored
      Now get_vmalloc_info() is in fs/proc/mmu.c.  There is no reason that this
      code must be here and it's implementation needs vmlist_lock and it iterate
      a vmlist which may be internal data structure for vmalloc.
      
      It is preferable that vmlist_lock and vmlist is only used in vmalloc.c
      for maintainability. So move the code to vmalloc.c
      Signed-off-by: default avatarJoonsoo Kim <js1304@gmail.com>
      Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Dave Anderson <anderson@redhat.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      db3808c1
    • Joonsoo Kim's avatar
      mm, vmalloc: change iterating a vmlist to find_vm_area() · ef932473
      Joonsoo Kim authored
      This patchset removes vm_struct list management after initializing
      vmalloc.  Adding and removing an entry to vmlist is linear time
      complexity, so it is inefficient.  If we maintain this list, overall
      time complexity of adding and removing area to vmalloc space is O(N),
      although we use rbtree for finding vacant place and it's time complexity
      is just O(logN).
      
      And vmlist and vmlist_lock is used many places of outside of vmalloc.c.
      It is preferable that we hide this raw data structure and provide
      well-defined function for supporting them, because it makes that they
      cannot mistake when manipulating theses structure and it makes us easily
      maintain vmalloc layer.
      
      For kexec and makedumpfile, I export vmap_area_list, instead of vmlist.
      This comes from Atsushi's recommendation.  For more information, please
      refer below link.  https://lkml.org/lkml/2012/12/6/184
      
      This patch:
      
      The purpose of iterating a vmlist is finding vm area with specific virtual
      address.  find_vm_area() is provided for this purpose and more efficient,
      because it uses a rbtree.  So change it.
      Signed-off-by: default avatarJoonsoo Kim <js1304@gmail.com>
      Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
      Acked-by: default avatarGuan Xuetao <gxt@mprc.pku.edu.cn>
      Acked-by: default avatarIngo Molnar <mingo@kernel.org>
      Acked-by: default avatarChris Metcalf <cmetcalf@tilera.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
      Cc: Dave Anderson <anderson@redhat.com>
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ef932473
    • Darrick J. Wong's avatar
      mm: make snapshotting pages for stable writes a per-bio operation · 71368511
      Darrick J. Wong authored
      Walking a bio's page mappings has proved problematic, so create a new
      bio flag to indicate that a bio's data needs to be snapshotted in order
      to guarantee stable pages during writeback.  Next, for the one user
      (ext3/jbd) of snapshotting, hook all the places where writes can be
      initiated without PG_writeback set, and set BIO_SNAP_STABLE there.
      
      We must also flag journal "metadata" bios for stable writeout, since
      file data can be written through the journal.  Finally, the
      MS_SNAP_STABLE mount flag (only used by ext3) is now superfluous, so get
      rid of it.
      
      [akpm@linux-foundation.org: rename _submit_bh()'s `flags' to `bio_flags', delobotomize the _submit_bh declaration]
      [akpm@linux-foundation.org: teeny cleanup]
      Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Artem Bityutskiy <dedekind1@gmail.com>
      Reviewed-by: default avatarJan Kara <jack@suse.cz>
      Cc: Jens Axboe <axboe@kernel.dk>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      71368511
    • Gerald Schaefer's avatar
      mm/hugetlb: add more arch-defined huge_pte functions · 106c992a
      Gerald Schaefer authored
      Commit abf09bed ("s390/mm: implement software dirty bits")
      introduced another difference in the pte layout vs.  the pmd layout on
      s390, thoroughly breaking the s390 support for hugetlbfs.  This requires
      replacing some more pte_xxx functions in mm/hugetlbfs.c with a
      huge_pte_xxx version.
      
      This patch introduces those huge_pte_xxx functions and their generic
      implementation in asm-generic/hugetlb.h, which will now be included on
      all architectures supporting hugetlbfs apart from s390.  This change
      will be a no-op for those architectures.
      
      [akpm@linux-foundation.org: fix warning]
      Signed-off-by: default avatarGerald Schaefer <gerald.schaefer@de.ibm.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Hillf Danton <dhillf@gmail.com>
      Acked-by: Michal Hocko <mhocko@suse.cz>	[for !s390 parts]
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Paul Mundt <lethal@linux-sh.org>
      Cc: "David S. Miller" <davem@davemloft.net>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      106c992a
    • Josh Triplett's avatar
      fs: don't compile in drop_caches.c when CONFIG_SYSCTL=n · 146732ce
      Josh Triplett authored
      drop_caches.c provides code only invokable via sysctl, so don't compile it
      in when CONFIG_SYSCTL=n.
      Signed-off-by: default avatarJosh Triplett <josh@joshtriplett.org>
      Acked-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      146732ce
    • Michal Hocko's avatar
      cgroup: remove css_get_next · 6d2488f6
      Michal Hocko authored
      Now that we have generic and well ordered cgroup tree walkers there is
      no need to keep css_get_next in the place.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Acked-by: default avatarLi Zefan <lizefan@huawei.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Ying Han <yinghan@google.com>
      Cc: Tejun Heo <htejun@gmail.com>
      Cc: Glauber Costa <glommer@parallels.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6d2488f6
    • Michal Hocko's avatar
      memcg: further simplify mem_cgroup_iter · 16248d8f
      Michal Hocko authored
      mem_cgroup_iter basically does two things currently.  It takes care of
      the house keeping (reference counting, raclaim cookie) and it iterates
      through a hierarchy tree (by using cgroup generic tree walk).  The code
      would be much more easier to follow if we move the iteration outside of
      the function (to __mem_cgrou_iter_next) so the distinction is more
      clear.  This patch doesn't introduce any functional changes.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Li Zefan <lizefan@huawei.com>
      Cc: Ying Han <yinghan@google.com>
      Cc: Tejun Heo <htejun@gmail.com>
      Cc: Glauber Costa <glommer@parallels.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      16248d8f
    • Michal Hocko's avatar
      memcg: simplify mem_cgroup_iter · 19f39402
      Michal Hocko authored
      The current implementation of mem_cgroup_iter has to consider both css
      and memcg to find out whether no group has been found (css==NULL - aka
      the loop is completed) and that no memcg is associated with the found
      node (!memcg - aka css_tryget failed because the group is no longer
      alive).  This leads to awkward tweaks like tests for css && !memcg to
      skip the current node.
      
      It will be much easier if we got rid off css variable altogether and
      only rely on memcg.  In order to do that the iteration part has to skip
      dead nodes.  This sounds natural to me and as a nice side effect we will
      get a simple invariant that memcg is always alive when non-NULL and all
      nodes have been visited otherwise.
      
      We could get rid of the surrounding while loop but keep it in for now to
      make review easier.  It will go away in the following patch.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Li Zefan <lizefan@huawei.com>
      Cc: Ying Han <yinghan@google.com>
      Cc: Tejun Heo <htejun@gmail.com>
      Cc: Glauber Costa <glommer@parallels.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      19f39402
    • Michal Hocko's avatar
      memcg: relax memcg iter caching · 5f578161
      Michal Hocko authored
      Now that the per-node-zone-priority iterator caches memory cgroups
      rather than their css ids we have to be careful and remove them from the
      iterator when they are on the way out otherwise they might live for
      unbounded amount of time even though their group is already gone (until
      the global/targeted reclaim triggers the zone under priority to find out
      the group is dead and let it to find the final rest).
      
      We can fix this issue by relaxing rules for the last_visited memcg.
      Instead of taking a reference to the css before it is stored into
      iter->last_visited we can just store its pointer and track the number of
      removed groups from each memcg's subhierarchy.
      
      This number would be stored into iterator everytime when a memcg is
      cached.  If the iter count doesn't match the curent walker root's one we
      will start from the root again.  The group counter is incremented
      upwards the hierarchy every time a group is removed.
      
      The iter_lock can be dropped because racing iterators cannot leak the
      reference anymore as the reference count is not elevated for
      last_visited when it is cached.
      
      Locking rules got a bit complicated by this change though.  The iterator
      primarily relies on rcu read lock which makes sure that once we see a
      valid last_visited pointer then it will be valid for the whole RCU walk.
      smp_rmb makes sure that dead_count is read before last_visited and
      last_dead_count while smp_wmb makes sure that last_visited is updated
      before last_dead_count so the up-to-date last_dead_count cannot point to
      an outdated last_visited.  css_tryget then makes sure that the
      last_visited is still alive in case the iteration races with the cached
      group removal (css is invalidated before mem_cgroup_css_offline
      increments dead_count).
      
      In short:
      mem_cgroup_iter
       rcu_read_lock()
       dead_count = atomic_read(parent->dead_count)
       smp_rmb()
       if (dead_count != iter->last_dead_count)
       	last_visited POSSIBLY INVALID -> last_visited = NULL
       if (!css_tryget(iter->last_visited))
       	last_visited DEAD -> last_visited = NULL
       next = find_next(last_visited)
       css_tryget(next)
       css_put(last_visited) 	// css would be invalidated and parent->dead_count
       			// incremented if this was the last reference
       iter->last_visited = next
       smp_wmb()
       iter->last_dead_count = dead_count
       rcu_read_unlock()
      
      cgroup_rmdir
       cgroup_destroy_locked
        atomic_add(CSS_DEACT_BIAS, &css->refcnt) // subsequent css_tryget fail
         mem_cgroup_css_offline
          mem_cgroup_invalidate_reclaim_iterators
           while(parent = parent_mem_cgroup)
           	atomic_inc(parent->dead_count)
        css_put(css) // last reference held by cgroup core
      
      Spotted by Ying Han.
      
      Original idea from Johannes Weiner.
      
      [akpm@linux-foundation.org: coding-style fixes]
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Ying Han <yinghan@google.com>
      Cc: Li Zefan <lizefan@huawei.com>
      Cc: Tejun Heo <htejun@gmail.com>
      Cc: Glauber Costa <glommer@parallels.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5f578161
    • Michal Hocko's avatar
      memcg: rework mem_cgroup_iter to use cgroup iterators · 542f85f9
      Michal Hocko authored
      mem_cgroup_iter curently relies on css->id when walking down a group
      hierarchy tree.  This is really awkward because the tree walk depends on
      the groups creation ordering.  The only guarantee is that a parent node is
      visited before its children.
      
      Example:
      
       1) mkdir -p a a/d a/b/c
       2) mkdir -a a/b/c a/d
      
      Will create the same trees but the tree walks will be different:
      
       1) a, d, b, c
       2) a, b, c, d
      
      Commit 574bd9f7 ("cgroup: implement generic child / descendant walk
      macros") has introduced generic cgroup tree walkers which provide either
      pre-order or post-order tree walk.  This patch converts css->id based
      iteration to pre-order tree walk to keep the semantic with the original
      iterator where parent is always visited before its subtree.
      
      cgroup_for_each_descendant_pre suggests using post_create and
      pre_destroy for proper synchronization with groups addidition resp.
      removal.  This implementation doesn't use those because a new memory
      cgroup is initialized sufficiently for iteration in mem_cgroup_css_alloc
      already and css reference counting enforces that the group is alive for
      both the last seen cgroup and the found one resp.  it signals that the
      group is dead and it should be skipped.
      
      If the reclaim cookie is used we need to store the last visited group
      into the iterator so we have to be careful that it doesn't disappear in
      the mean time.  Elevated reference count on the css keeps it alive even
      though the group have been removed (parked waiting for the last dput so
      that it can be freed).
      
      Per node-zone-prio iter_lock has been introduced to ensure that
      css_tryget and iter->last_visited is set atomically.  Otherwise two
      racing walkers could both take a references and only one release it
      leading to a css leak (which pins cgroup dentry).
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Li Zefan <lizefan@huawei.com>
      Cc: Ying Han <yinghan@google.com>
      Cc: Tejun Heo <htejun@gmail.com>
      Cc: Glauber Costa <glommer@parallels.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      542f85f9
    • Michal Hocko's avatar
      memcg: keep prev's css alive for the whole mem_cgroup_iter · c40046f3
      Michal Hocko authored
      The patchset tries to make mem_cgroup_iter saner in the way how it walks
      hierarchies.  css->id based traversal is far from being ideal as it is not
      deterministic because it depends on the creation ordering.  Additional to
      that css_id is considered a burden for cgroup maintainers because it is
      quite some code and memcg is the last user of it.  After this series only
      the swap accounting uses css_id but that one will follow up later.
      
      Diffstat (if we exclude removed/added comments) looks quite
      promising. We got rid of some code:
      
        $ git diff mmotm... | grep -v "^[+-][[:space:]]*[/ ]\*" | diffstat
         b/include/linux/cgroup.h |    3 ---
         kernel/cgroup.c          |   33 ---------------------------------
         mm/memcontrol.c          |    4 +++-
         3 files changed, 3 insertions(+), 37 deletions(-)
      
      The first patch is just preparatory and it changes when we release css of
      the previously returned memcg.  Nothing controlversial.
      
      The second patch is the core of the patchset and it replaces css_get_next
      based on css_id by the generic cgroup pre-order.  This brings some
      chalanges for the last visited group caching during the reclaim
      (mem_cgroup_per_zone::reclaim_iter).  We have to use memcg pointers
      directly now which means that we have to keep a reference to those groups'
      css to keep them alive.
      
      I also folded iter_lock introduced by https://lkml.org/lkml/2013/1/3/295
      in the previous version into this patch.  Johannes felt the race I was
      describing should be mostly harmless and I haven't been able to trigger it
      so the lock doesn't deserve its own patch.  It is still needed
      temporarily, though, because the reference counting on iter->last_visited
      depends on it.  It will go away with the next patch.
      
      The next patch fixups an unbounded cgroup removal holdoff caused by the
      elevated css refcount.  The issue has been observed by Ying Han.  Johannes
      wasn't impressed by the previous version of the fix
      (https://lkml.org/lkml/2013/2/8/379) which cleaned up pending references
      during mem_cgroup_css_offline when a group is removed.  He has suggested a
      different way when the iterator checks whether a cached memcg is still
      valid or no.  More on that in the patch but the basic idea is that every
      memcg tracks the number removed subgroups and iterator records this number
      when a group is cached.  These numbers are checked before
      iter->last_visited is about to be used and the iteration is restarted if
      it is invalid.
      
      The fourth and fifth patches are an attempt for simplification of the
      mem_cgroup_iter.  css juggling is removed and the iteration logic is moved
      to a helper so that the reference counting and iteration are separated.
      
      The last patch just removes css_get_next as there is no user for it any
      longer.
      
      My testing looked as follows:
              A (use_hierarchy=1, limit_in_bytes=150M)
             /|\
            1 2 3
      
      Children groups were created so that the number is never higher than 3 and
      their limits were random between 50-100M.  Each group hosts a kernel build
      (starting with tar -xf so the tree is not shared and make -jNUM_CPUs/3)
      and terminated after random time - up to 5 minutes) and then it is
      removed.
      
      This should exercise both leaf and hierarchical reclaim as well as races
      with cgroup removals and debugging messages I added on top proved that.
      100 groups were created during the test.
      
      This patch:
      
      css reference counting keeps the cgroup alive even though it has been
      already removed.  mem_cgroup_iter relies on this fact and takes a
      reference to the returned group.  The reference is then released on the
      next iteration or mem_cgroup_iter_break.  mem_cgroup_iter currently
      releases the reference right after it gets the last css_id.
      
      This is correct because neither prev's memcg nor cgroup are accessed after
      then.  This will change in the next patch so we need to hold the group
      alive a bit longer so let's move the css_put at the end of the function.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Li Zefan <lizefan@huawei.com>
      Cc: Ying Han <yinghan@google.com>
      Cc: Tejun Heo <htejun@gmail.com>
      Cc: Glauber Costa <glommer@parallels.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c40046f3
    • Jiang Liu's avatar
      mm/x86: use free_highmem_page() to free highmem pages into buddy system · 5e7ccf86
      Jiang Liu authored
      Use helper function free_highmem_page() to free highmem pages into
      the buddy system.
      Signed-off-by: default avatarJiang Liu <jiang.liu@huawei.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Cong Wang <amwang@redhat.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: Attilio Rao <attilio.rao@citrix.com>
      Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      Reviewed-by: default avatarPekka Enberg <penberg@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5e7ccf86
    • Jiang Liu's avatar
      mm/um: use free_highmem_page() to free highmem pages into buddy system · 5b472b20
      Jiang Liu authored
      Use helper function free_highmem_page() to free highmem pages into
      the buddy system.
      Signed-off-by: default avatarJiang Liu <jiang.liu@huawei.com>
      Cc: Jeff Dike <jdike@addtoit.com>
      Cc: Richard Weinberger <richard@nod.at>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5b472b20
    • Jiang Liu's avatar
      mm/SPARC: use free_highmem_page() to free highmem pages into buddy system · 32e1a109
      Jiang Liu authored
      Use helper function free_highmem_page() to free highmem pages into
      the buddy system.
      Signed-off-by: default avatarJiang Liu <jiang.liu@huawei.com>
      Cc: "David S. Miller" <davem@davemloft.net>
      Acked-by: default avatarSam Ravnborg <sam@ravnborg.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      32e1a109
    • Jiang Liu's avatar
      mm/PPC: use free_highmem_page() to free highmem pages into buddy system · 7db6f78c
      Jiang Liu authored
      Use helper function free_highmem_page() to free highmem pages into
      the buddy system.
      Signed-off-by: default avatarJiang Liu <jiang.liu@huawei.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Jiang Liu <jiang.liu@huawei.com>
      Cc: Alexander Graf <agraf@suse.de>
      Cc: "Suzuki K. Poulose" <suzuki@in.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7db6f78c
    • Jiang Liu's avatar
      mm/MIPS: use free_highmem_page() to free highmem pages into buddy system · 0f354869
      Jiang Liu authored
      Use helper function free_highmem_page() to free highmem pages into
      the buddy system.
      Signed-off-by: default avatarJiang Liu <jiang.liu@huawei.com>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: David Daney <david.daney@cavium.com>
      Cc: Cong Wang <amwang@redhat.com>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0f354869
    • Jiang Liu's avatar
      mm/microblaze: use free_highmem_page() to free highmem pages into buddy system · ec601a34
      Jiang Liu authored
      Use helper function free_highmem_page() to free highmem pages into
      the buddy system.
      Signed-off-by: default avatarJiang Liu <jiang.liu@huawei.com>
      Cc: Michal Simek <monstr@monstr.eu>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ec601a34
    • Jiang Liu's avatar
      mm/metag: use free_highmem_page() to free highmem pages into buddy system · a564496e
      Jiang Liu authored
      Use helper function free_highmem_page() to free highmem pages into
      the buddy system.
      Signed-off-by: default avatarJiang Liu <jiang.liu@huawei.com>
      Cc: James Hogan <james.hogan@imgtec.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a564496e