linux/mm, branch v3.0.18

mm: fix NULL ptr dereference in __count_immobile_pages

2012-01-26T01:25:05Z

commit 687875fb7de4a95223af20ee024282fa9099f860 upstream. Fix the following NULL ptr dereference caused by cat /sys/devices/system/memory/memory0/removable Pid: 13979, comm: sed Not tainted 3.0.13-0.5-default #1 IBM BladeCenter LS21 -[7971PAM]-/Server Blade RIP: __count_immobile_pages+0x4/0x100 Process sed (pid: 13979, threadinfo ffff880221c36000, task ffff88022e788480) Call Trace: is_pageblock_removable_nolock+0x34/0x40 is_mem_section_removable+0x74/0xf0 show_mem_removable+0x41/0x70 sysfs_read_file+0xfe/0x1c0 vfs_read+0xc7/0x130 sys_read+0x53/0xa0 system_call_fastpath+0x16/0x1b We are crashing because we are trying to dereference NULL zone which came from pfn=0 (struct page ffffea0000000000). According to the boot log this page is marked reserved: e820 update range: 0000000000000000 - 0000000000010000 (usable) ==> (reserved) and early_node_map confirms that: early_node_map[3] active PFN ranges 1: 0x00000010 -> 0x0000009c 1: 0x00000100 -> 0x000bffa3 1: 0x00100000 -> 0x00240000 The problem is that memory_present works in PAGE_SECTION_MASK aligned blocks so the reserved range sneaks into the the section as well. This also means that free_area_init_node will not take care of those reserved pages and they stay uninitialized. When we try to read the removable status we walk through all available sections and hope that the zone is valid for all pages in the section. But this is not true in this case as the zone and nid are not initialized. We have only one node in this particular case and it is marked as node=1 (rather than 0) and that made the problem visible because page_to_nid will return 0 and there are no zones on the node. Let's check that the zone is valid and that the given pfn falls into its boundaries and mark the section not removable. This might cause some false positives, probably, but we do not have any sane way to find out whether the page is reserved by the platform or it is just not used for whatever other reasons. Signed-off-by: Michal Hocko Acked-by: Mel Gorman Cc: KAMEZAWA Hiroyuki Cc: Andrea Arcangeli Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

memcg: add mem_cgroup_replace_page_cache() to fix LRU issue

2012-01-26T01:24:43Z

commit ab936cbcd02072a34b60d268f94440fd5cf1970b upstream. Commit ef6a3c6311 ("mm: add replace_page_cache_page() function") added a function replace_page_cache_page(). This function replaces a page in the radix-tree with a new page. WHen doing this, memory cgroup needs to fix up the accounting information. memcg need to check PCG_USED bit etc. In some(many?) cases, 'newpage' is on LRU before calling replace_page_cache(). So, memcg's LRU accounting information should be fixed, too. This patch adds mem_cgroup_replace_page_cache() and removes the old hooks. In that function, old pages will be unaccounted without touching res_counter and new page will be accounted to the memcg (of old page). WHen overwriting pc->mem_cgroup of newpage, take zone->lru_lock and avoid races with LRU handling. Background: replace_page_cache_page() is called by FUSE code in its splice() handling. Here, 'newpage' is replacing oldpage but this newpage is not a newly allocated page and may be on LRU. LRU mis-accounting will be critical for memory cgroup because rmdir() checks the whole LRU is empty and there is no account leak. If a page is on the other LRU than it should be, rmdir() will fail. This bug was added in March 2011, but no bug report yet. I guess there are not many people who use memcg and FUSE at the same time with upstream kernels. The result of this bug is that admin cannot destroy a memcg because of account leak. So, no panic, no deadlock. And, even if an active cgroup exist, umount can succseed. So no problem at shutdown. Signed-off-by: KAMEZAWA Hiroyuki Acked-by: Johannes Weiner Acked-by: Michal Hocko Cc: Miklos Szeredi Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: hugetlb: fix non-atomic enqueue of huge page

2012-01-06T22:14:00Z

commit b0365c8d0cb6e79eb5f21418ae61ab511f31b575 upstream. If a huge page is enqueued under the protection of hugetlb_lock, then the operation is atomic and safe. Signed-off-by: Hillf Danton Reviewed-by: Michal Hocko Acked-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

memcg: keep root group unchanged if creation fails

2012-01-06T22:13:55Z

commit a41c58a6665cc995e237303b05db42100b71b65e upstream. If the request is to create non-root group and we fail to meet it, we should leave the root unchanged. Signed-off-by: Hillf Danton Signed-off-by: Hugh Dickins Acked-by: KAMEZAWA Hiroyuki Acked-by: Michal Hocko Cc: Balbir Singh Cc: David Rientjes Cc: Andrea Arcangeli Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

vfs: __read_cache_page should use gfp argument rather than GFP_KERNEL

2012-01-06T22:13:54Z

commit e6f67b8c05f5e129e126f4409ddac6f25f58ffcb upstream. lockdep reports a deadlock in jfs because a special inode's rw semaphore is taken recursively. The mapping's gfp mask is GFP_NOFS, but is not used when __read_cache_page() calls add_to_page_cache_lru(). Signed-off-by: Dave Kleikamp Acked-by: Hugh Dickins Acked-by: Al Viro Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

oom: fix integer overflow of points in oom_badness

2012-01-06T22:13:51Z

commit ff05b6f7ae762b6eb464183eec994b28ea09f6dd upstream. An integer overflow will happen on 64bit archs if task's sum of rss, swapents and nr_ptes exceeds (2^31)/1000 value. This was introduced by commit f755a04 oom: use pte pages in OOM score where the oom score computation was divided into several steps and it's no longer computed as one expression in unsigned long(rss, swapents, nr_pte are unsigned long), where the result value assigned to points(int) is in range(1..1000). So there could be an int overflow while computing 176 points *= 1000; and points may have negative value. Meaning the oom score for a mem hog task will be one. 196 if (points <= 0) 197 return 1; For example: [ 3366] 0 3366 35390480 24303939 5 0 0 oom01 Out of memory: Kill process 3366 (oom01) score 1 or sacrifice child Here the oom1 process consumes more than 24303939(rss)*4096~=92GB physical memory, but it's oom score is one. In this situation the mem hog task is skipped and oom killer kills another and most probably innocent task with oom score greater than one. The points variable should be of type long instead of int to prevent the int overflow. Signed-off-by: Frantisek Hrbata Acked-by: KOSAKI Motohiro Acked-by: Oleg Nesterov Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

percpu: fix per_cpu_ptr_to_phys() handling of non-page-aligned addresses

2012-01-06T22:13:50Z

commit 9f57bd4d6dc69a4e3bf43044fa00fcd24dd363e3 upstream. per_cpu_ptr_to_phys() incorrectly rounds up its result for non-kmalloc case to the page boundary, which is bogus for any non-page-aligned address. This affects the only in-tree user of this function - sysfs handler for per-cpu 'crash_notes' physical address. The trouble is that the crash_notes per-cpu variable is not page-aligned: crash_notes = 0xc08e8ed4 PER-CPU OFFSET VALUES: CPU 0: 3711f000 CPU 1: 37129000 CPU 2: 37133000 CPU 3: 3713d000 So, the per-cpu addresses are: crash_notes on CPU 0: f7a07ed4 => phys 36b57ed4 crash_notes on CPU 1: f7a11ed4 => phys 36b4ded4 crash_notes on CPU 2: f7a1bed4 => phys 36b43ed4 crash_notes on CPU 3: f7a25ed4 => phys 36b39ed4 However, /sys/devices/system/cpu/cpu*/crash_notes says: /sys/devices/system/cpu/cpu0/crash_notes: 36b57000 /sys/devices/system/cpu/cpu1/crash_notes: 36b4d000 /sys/devices/system/cpu/cpu2/crash_notes: 36b43000 /sys/devices/system/cpu/cpu3/crash_notes: 36b39000 As you can see, all values are rounded down to a page boundary. Consequently, this is where kexec sets up the NOTE segments, and thus where the secondary kernel is looking for them. However, when the first kernel crashes, it saves the notes to the unaligned addresses, where they are not found. Fix it by adding offset_in_page() to the translated page address. -tj: Combined Eugene's and Petr's commit messages. Signed-off-by: Eugene Surovegin Signed-off-by: Tejun Heo Reported-by: Petr Tesarik Signed-off-by: Greg Kroah-Hartman

percpu: fix chunk range calculation

2011-12-21T20:57:37Z

commit a855b84c3d8c73220d4d3cd392a7bee7c83de70e upstream. Percpu allocator recorded the cpus which map to the first and last units in pcpu_first/last_unit_cpu respectively and used them to determine the address range of a chunk - e.g. it assumed that the first unit has the lowest address in a chunk while the last unit has the highest address. This simply isn't true. Groups in a chunk can have arbitrary positive or negative offsets from the previous one and there is no guarantee that the first unit occupies the lowest offset while the last one the highest. Fix it by actually comparing unit offsets to determine cpus occupying the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu to pcpu_low/high_unit_cpu to avoid confusion. The chunk address range is used to flush cache on vmalloc area map/unmap and decide whether a given address is in the first chunk by per_cpu_ptr_to_phys() and the bug was discovered by invalid per_cpu_ptr_to_phys() translation for crash_note. Kudos to Dave Young for tracking down the problem. Signed-off-by: Tejun Heo Reported-by: WANG Cong Reported-by: Dave Young Tested-by: Dave Young LKML-Reference: <4EC21F67.10905@redhat.com> Signed-off-by: Thomas Renninger Signed-off-by: Greg Kroah-Hartman

mm: vmalloc: check for page allocation failure before vmlist insertion

2011-12-21T20:57:36Z

commit 1368edf0647ac112d8cfa6ce47257dc950c50f5c upstream. Commit f5252e00 ("mm: avoid null pointer access in vm_struct via /proc/vmallocinfo") adds newly allocated vm_structs to the vmlist after it is fully initialised. Unfortunately, it did not check that __vmalloc_area_node() successfully populated the area. In the event of allocation failure, the vmalloc area is freed but the pointer to freed memory is inserted into the vmlist leading to a a crash later in get_vmalloc_info(). This patch adds a check for ____vmalloc_area_node() failure within __vmalloc_node_range. It does not use "goto fail" as in the previous error path as a warning was already displayed by __vmalloc_area_node() before it called vfree in its failure path. Credit goes to Luciano Chavez for doing all the real work of identifying exactly where the problem was. Signed-off-by: Mel Gorman Reported-by: Luciano Chavez Tested-by: Luciano Chavez Reviewed-by: Rik van Riel Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: Ensure that pfn_valid() is called once per pageblock when reserving pageblocks

2011-12-21T20:57:36Z

commit d021563888312018ca65681096f62e36c20e63cc upstream. setup_zone_migrate_reserve() expects that zone->start_pfn starts at pageblock_nr_pages aligned pfn otherwise we could access beyond an existing memblock resulting in the following panic if CONFIG_HOLES_IN_ZONE is not configured and we do not check pfn_valid: IP: [] setup_zone_migrate_reserve+0xcd/0x180 *pdpt = 0000000000000000 *pde = f000ff53f000ff53 Oops: 0000 [#1] SMP Pid: 1, comm: swapper Not tainted 3.0.7-0.7-pae #1 VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform EIP: 0060:[] EFLAGS: 00010006 CPU: 0 EIP is at setup_zone_migrate_reserve+0xcd/0x180 EAX: 000c0000 EBX: f5801fc0 ECX: 000c0000 EDX: 00000000 ESI: 000c01fe EDI: 000c01fe EBP: 00140000 ESP: f2475f58 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 Process swapper (pid: 1, ti=f2474000 task=f2472cd0 task.ti=f2474000) Call Trace: [] __setup_per_zone_wmarks+0xec/0x160 [] setup_per_zone_wmarks+0xf/0x20 [] init_per_zone_wmark_min+0x27/0x86 [] do_one_initcall+0x2b/0x160 [] kernel_init+0xbe/0x157 [] kernel_thread_helper+0x6/0xd Code: a5 39 f5 89 f7 0f 46 fd 39 cf 76 40 8b 03 f6 c4 08 74 32 eb 91 90 89 c8 c1 e8 0e 0f be 80 80 2f 86 c0 8b 14 85 60 2f 86 c0 89 c8 <2b> 82 b4 12 00 00 c1 e0 05 03 82 ac 12 00 00 8b 00 f6 c4 08 0f EIP: [] setup_zone_migrate_reserve+0xcd/0x180 SS:ESP 0068:f2475f58 CR2: 00000000000012b4 We crashed in pageblock_is_reserved() when accessing pfn 0xc0000 because highstart_pfn = 0x36ffe. The issue was introduced in 3.0-rc1 by 6d3163ce ("mm: check if any page in a pageblock is reserved before marking it MIGRATE_RESERVE"). Make sure that start_pfn is always aligned to pageblock_nr_pages to ensure that pfn_valid s always called at the start of each pageblock. Architectures with holes in pageblocks will be correctly handled by pfn_valid_within in pageblock_is_reserved. Signed-off-by: Michal Hocko Signed-off-by: Mel Gorman Tested-by: Dang Bo Reviewed-by: KAMEZAWA Hiroyuki Cc: Andrea Arcangeli Cc: David Rientjes Cc: Arve Hjnnevg Cc: KOSAKI Motohiro Cc: John Stultz Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman