- 03 Jul, 2013 40 commits
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Mel Gorman authored
Currently kswapd queues dirty pages for writeback if scanning at an elevated priority but the priority kswapd scans at is not related to the number of unqueued dirty encountered. Since commit "mm: vmscan: Flatten kswapd priority loop", the priority is related to the size of the LRU and the zone watermark which is no indication as to whether kswapd should write pages or not. This patch tracks if an excessive number of unqueued dirty pages are being encountered at the end of the LRU. If so, it indicates that dirty pages are being recycled before flusher threads can clean them and flags the zone so that kswapd will start writing pages until the zone is balanced. Signed-off-by:
Mel Gorman <mgorman@suse.de> Acked-by:
Johannes Weiner <hannes@cmpxchg.org> Reviewed-by:
Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by:
Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Mel Gorman authored
Page reclaim at priority 0 will scan the entire LRU as priority 0 is considered to be a near OOM condition. Kswapd can reach priority 0 quite easily if it is encountering a large number of pages it cannot reclaim such as pages under writeback. When this happens, kswapd reclaims very aggressively even though there may be no real risk of allocation failure or OOM. This patch prevents kswapd reaching priority 0 and trying to reclaim the world. Direct reclaimers will still reach priority 0 in the event of an OOM situation. Signed-off-by:
Rik van Riel <riel@redhat.com> Acked-by:
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Mel Gorman authored
In the past, kswapd makes a decision on whether to compact memory after the pgdat was considered balanced. This more or less worked but it is late to make such a decision and does not fit well now that kswapd makes a decision whether to exit the zone scanning loop depending on reclaim progress. This patch will compact a pgdat if at least the requested number of pages were reclaimed from unbalanced zones for a given priority. If any zone is currently balanced, kswapd will not call compaction as it is expected the necessary pages are already available. Signed-off-by:
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Mel Gorman authored
kswapd stops raising the scanning priority when at least SWAP_CLUSTER_MAX pages have been reclaimed or the pgdat is considered balanced. It then rechecks if it needs to restart at DEF_PRIORITY and whether high-order reclaim needs to be reset. This is not wrong per-se but it is confusing to follow and forcing kswapd to stay at DEF_PRIORITY may require several restarts before it has scanned enough pages to meet the high watermark even at 100% efficiency. This patch irons out the logic a bit by controlling when priority is raised and removing the "goto loop_again". This patch has kswapd raise the scanning priority until it is scanning enough pages that it could meet the high watermark in one shrink of the LRU lists if it is able to reclaim at 100% efficiency. It will not raise the scanning prioirty higher unless it is failing to reclaim any pages. To avoid infinite looping for high-order allocation requests kswapd will not reclaim for high-order allocations when it has reclaimed at least twice the number of pages as the allocation request. Signed-off-by:
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Mel Gorman authored
Simplistically, the anon and file LRU lists are scanned proportionally depending on the value of vm.swappiness although there are other factors taken into account by get_scan_count(). The patch "mm: vmscan: Limit the number of pages kswapd reclaims" limits the number of pages kswapd reclaims but it breaks this proportional scanning and may evenly shrink anon/file LRUs regardless of vm.swappiness. This patch preserves the proportional scanning and reclaim. It does mean that kswapd will reclaim more than requested but the number of pages will be related to the high watermark. [mhocko@suse.cz: Correct proportional reclaim for memcg and simplify] [kamezawa.hiroyu@jp.fujitsu.com: Recalculate scan based on target] [hannes@cmpxchg.org: Account for already scanned pages properly] Signed-off-by:
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by:
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Mel Gorman authored
This series does not fix all the current known problems with reclaim but it addresses one important swapping bug when there is background IO. Changelog since V3 - Drop the slab shrink changes in light of Glaubers series and discussions highlighted that there were a number of potential problems with the patch. (mel) - Rebased to 3.10-rc1 Changelog since V2 - Preserve ratio properly for proportional scanning (kamezawa) Changelog since V1 - Rename ZONE_DIRTY to ZONE_TAIL_LRU_DIRTY (andi) - Reformat comment in shrink_page_list (andi) - Clarify some comments (dhillf) - Rework how the proportional scanning is preserved - Add PageReclaim check before kswapd starts writeback - Reset sc.nr_reclaimed on every full zone scan Kswapd and page reclaim behaviour has been screwy in one way or the other for a long time. Very broadly speaking it worked in the far past because machines were limited in memory so it did not have that many pages to scan and it stalled congestion_wait() frequently to prevent it going completely nuts. In recent times it has behaved very unsatisfactorily with some of the problems compounded by the removal of stall logic and the introduction of transparent hugepage support with high-order reclaims. There are many variations of bugs that are rooted in this area. One example is reports of a large copy operations or backup causing the machine to grind to a halt or applications pushed to swap. Sometimes in low memory situations a large percentage of memory suddenly gets reclaimed. In other cases an application starts and kswapd hits 100% CPU usage for prolonged periods of time and so on. There is now talk of introducing features like an extra free kbytes tunable to work around aspects of the problem instead of trying to deal with it. It's compounded by the problem that it can be very workload and machine specific. This series aims at addressing some of the worst of these problems without attempting to fundmentally alter how page reclaim works. Patches 1-2 limits the number of pages kswapd reclaims while still obeying the anon/file proportion of the LRUs it should be scanning. Patches 3-4 control how and when kswapd raises its scanning priority and deletes the scanning restart logic which is tricky to follow. Patch 5 notes that it is too easy for kswapd to reach priority 0 when scanning and then reclaim the world. Down with that sort of thing. Patch 6 notes that kswapd starts writeback based on scanning priority which is not necessarily related to dirty pages. It will have kswapd writeback pages if a number of unqueued dirty pages have been recently encountered at the tail of the LRU. Patch 7 notes that sometimes kswapd should stall waiting on IO to complete to reduce LRU churn and the likelihood that it'll reclaim young clean pages or push applications to swap. It will cause kswapd to block on IO if it detects that pages being reclaimed under writeback are recycling through the LRU before the IO completes. Patchies 8-9 are cosmetic but balance_pgdat() is easier to follow after they are applied. This was tested using memcached+memcachetest while some background IO was in progress as implemented by the parallel IO tests implement in MM Tests. memcachetest benchmarks how many operations/second memcached can service and it is run multiple times. It starts with no background IO and then re-runs the test with larger amounts of IO in the background to roughly simulate a large copy in progress. The expectation is that the IO should have little or no impact on memcachetest which is running entirely in memory. 3.10.0-rc1 3.10.0-rc1 vanilla lessdisrupt-v4 Ops memcachetest-0M 22155.00 ( 0.00%) 22180.00 ( 0.11%) Ops memcachetest-715M 22720.00 ( 0.00%) 22355.00 ( -1.61%) Ops memcachetest-2385M 3939.00 ( 0.00%) 23450.00 (495.33%) Ops memcachetest-4055M 3628.00 ( 0.00%) 24341.00 (570.92%) Ops io-duration-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops io-duration-715M 12.00 ( 0.00%) 7.00 ( 41.67%) Ops io-duration-2385M 118.00 ( 0.00%) 21.00 ( 82.20%) Ops io-duration-4055M 162.00 ( 0.00%) 36.00 ( 77.78%) Ops swaptotal-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swaptotal-715M 140134.00 ( 0.00%) 18.00 ( 99.99%) Ops swaptotal-2385M 392438.00 ( 0.00%) 0.00 ( 0.00%) Ops swaptotal-4055M 449037.00 ( 0.00%) 27864.00 ( 93.79%) Ops swapin-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-715M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-2385M 148031.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-4055M 135109.00 ( 0.00%) 0.00 ( 0.00%) Ops minorfaults-0M 1529984.00 ( 0.00%) 1530235.00 ( -0.02%) Ops minorfaults-715M 1794168.00 ( 0.00%) 1613750.00 ( 10.06%) Ops minorfaults-2385M 1739813.00 ( 0.00%) 1609396.00 ( 7.50%) Ops minorfaults-4055M 1754460.00 ( 0.00%) 1614810.00 ( 7.96%) Ops majorfaults-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops majorfaults-715M 185.00 ( 0.00%) 180.00 ( 2.70%) Ops majorfaults-2385M 24472.00 ( 0.00%) 101.00 ( 99.59%) Ops majorfaults-4055M 22302.00 ( 0.00%) 229.00 ( 98.97%) Note how the vanilla kernels performance collapses when there is enough IO taking place in the background. This drop in performance is part of what users complain of when they start backups. Note how the swapin and major fault figures indicate that processes were being pushed to swap prematurely. With the series applied, there is no noticable performance drop and while there is still some swap activity, it's tiny. 20 iterations of this test were run in total and averaged. Every 5 iterations, additional IO was generated in the background using dd to measure how the workload was impacted. The 0M, 715M, 2385M and 4055M subblock refer to the amount of IO going on in the background at each iteration. So memcachetest-2385M is reporting how many transactions/second memcachetest recorded on average over 5 iterations while there was 2385M of IO going on in the ground. There are six blocks of information reported here memcachetest is the transactions/second reported by memcachetest. In the vanilla kernel note that performance drops from around 22K/sec to just under 4K/second when there is 2385M of IO going on in the background. This is one type of performance collapse users complain about if a large cp or backup starts in the background io-duration refers to how long it takes for the background IO to complete. It's showing that with the patched kernel that the IO completes faster while not interfering with the memcache workload swaptotal is the total amount of swap traffic. With the patched kernel, the total amount of swapping is much reduced although it is still not zero. swapin in this case is an indication as to whether we are swap trashing. The closer the swapin/swapout ratio is to 1, the worse the trashing is. Note with the patched kernel that there is no swapin activity indicating that all the pages swapped were really inactive unused pages. minorfaults are just minor faults. An increased number of minor faults can indicate that page reclaim is unmapping the pages but not swapping them out before they are faulted back in. With the patched kernel, there is only a small change in minor faults majorfaults are just major faults in the target workload and a high number can indicate that a workload is being prematurely swapped. With the patched kernel, major faults are much reduced. As there are no swapin's recorded so it's not being swapped. The likely explanation is that that libraries or configuration files used by the workload during startup get paged out by the background IO. Overall with the series applied, there is no noticable performance drop due to background IO and while there is still some swap activity, it's tiny and the lack of swapins imply that the swapped pages were inactive and unused. 3.10.0-rc1 3.10.0-rc1 vanilla lessdisrupt-v4 Page Ins 1234608 101892 Page Outs 12446272 11810468 Swap Ins 283406 0 Swap Outs 698469 27882 Direct pages scanned 0 136480 Kswapd pages scanned 6266537 5369364 Kswapd pages reclaimed 1088989 930832 Direct pages reclaimed 0 120901 Kswapd efficiency 17% 17% Kswapd velocity 5398.371 4635.115 Direct efficiency 100% 88% Direct velocity 0.000 117.817 Percentage direct scans 0% 2% Page writes by reclaim 1655843 4009929 Page writes file 957374 3982047 Page writes anon 698469 27882 Page reclaim immediate 5245 1745 Page rescued immediate 0 0 Slabs scanned 33664 25216 Direct inode steals 0 0 Kswapd inode steals 19409 778 Kswapd skipped wait 0 0 THP fault alloc 35 30 THP collapse alloc 472 401 THP splits 27 22 THP fault fallback 0 0 THP collapse fail 0 1 Compaction stalls 0 4 Compaction success 0 0 Compaction failures 0 4 Page migrate success 0 0 Page migrate failure 0 0 Compaction pages isolated 0 0 Compaction migrate scanned 0 0 Compaction free scanned 0 0 Compaction cost 0 0 NUMA PTE updates 0 0 NUMA hint faults 0 0 NUMA hint local faults 0 0 NUMA pages migrated 0 0 AutoNUMA cost 0 0 Unfortunately, note that there is a small amount of direct reclaim due to kswapd no longer reclaiming the world. ftrace indicates that the direct reclaim stalls are mostly harmless with the vast bulk of the stalls incurred by dd 23 tclsh-3367 38 memcachetest-13733 49 memcachetest-12443 57 tee-3368 1541 dd-13826 1981 dd-12539 A consequence of the direct reclaim for dd is that the processes for the IO workload may show a higher system CPU usage. There is also a risk that kswapd not reclaiming the world may mean that it stays awake balancing zones, does not stall on the appropriate events and continually scans pages it cannot reclaim consuming CPU. This will be visible as continued high CPU usage but in my own tests I only saw a single spike lasting less than a second and I did not observe any problems related to reclaim while running the series on my desktop. This patch: The number of pages kswapd can reclaim is bound by the number of pages it scans which is related to the size of the zone and the scanning priority. In many cases the priority remains low because it's reset every SWAP_CLUSTER_MAX reclaimed pages but in the event kswapd scans a large number of pages it cannot reclaim, it will raise the priority and potentially discard a large percentage of the zone as sc->nr_to_reclaim is ULONG_MAX. The user-visible effect is a reclaim "spike" where a large percentage of memory is suddenly freed. It would be bad enough if this was just unused memory but because of how anon/file pages are balanced it is possible that applications get pushed to swap unnecessarily. This patch limits the number of pages kswapd will reclaim to the high watermark. Reclaim will still overshoot due to it not being a hard limit as shrink_lruvec() will ignore the sc.nr_to_reclaim at DEF_PRIORITY but it prevents kswapd reclaiming the world at higher priorities. The number of pages it reclaims is not adjusted for high-order allocations as kswapd will reclaim excessively if it is to balance zones for high-order allocations. Signed-off-by: -
Cody P Schafer authored
When memory hotplug is triggered, we call pageset_init() on per-cpu-pagesets which both contain pages and are in use, causing both the leakage of those pages and (potentially) bad behaviour if a page is allocated from a pageset while it is being cleared. Avoid this by factoring out pageset_set_high_and_batch() (which contains all needed logic too set a pageset's ->high and ->batch inrespective of system state) from zone_pageset_init() and using the new pageset_set_high_and_batch() instead of zone_pageset_init() in zone_pcp_update(). Signed-off-by:
Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Signed-off-by:
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Cody P Schafer authored
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Cody P Schafer authored
Previously, zone_pcp_update() called pageset_set_batch() directly, essentially assuming that percpu_pagelist_fraction == 0. Correct this by calling zone_pageset_init(), which chooses the appropriate ->batch and ->high calculations. Signed-off-by:
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Cody P Schafer authored
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Cody P Schafer authored
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Cody P Schafer authored
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Cody P Schafer authored
Simply moves calculation of the new 'high' value outside the for_each_possible_cpu() loop, as it does not depend on the cpu. Signed-off-by:
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Cody P Schafer authored
zone_pcp_update()'s goal is to adjust the ->high and ->mark members of a percpu pageset based on a zone's ->managed_pages. We don't need to drain the entire percpu pageset just to modify these fields. This lets us avoid calling setup_pageset() (and the draining required to call it) and instead allows simply setting the fields' values (with some attention paid to memory barriers to prevent the relationship between ->batch and ->high from being thrown off). This does change the behavior of zone_pcp_update() as the percpu pagesets will not be drained when zone_pcp_update() is called (they will end up being shrunk, not completely drained, later when a 0-order page is freed in free_hot_cold_page()). Signed-off-by:
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Cody P Schafer authored
pcp->batch could change at any point, avoid relying on it being a stable value. Signed-off-by:
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Cody P Schafer authored
Introduce pageset_update() to perform a safe transision from one set of pcp->{batch,high} to a new set using memory barriers. This ensures that batch is always set to a safe value (1) prior to updating high, and ensure that high is fully updated before setting the real value of batch. It avoids ->batch ever rising above ->high. Suggested by Gilad Ben-Yossef in these threads: https://lkml.org/lkml/2013/4/9/23 https://lkml.org/lkml/2013/4/10/49 Also reproduces his proposed comment. Signed-off-by:Gilad Ben-Yossef <gilad@benyossef.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by:
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Cody P Schafer authored
Because we are going to rely upon a careful transision between old and new ->high and ->batch values using memory barriers and will remove stop_machine(), we need to prevent multiple updaters from interweaving their memory writes. Add a simple mutex to protect both update loops. Signed-off-by:
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Cody P Schafer authored
"Problems" with the current code: 1: there is a lack of synchronization in setting ->high and ->batch in percpu_pagelist_fraction_sysctl_handler() 2: stop_machine() in zone_pcp_update() is unnecissary. 3: zone_pcp_update() does not consider the case where percpu_pagelist_fraction is non-zero To fix: 1: add memory barriers, a safe ->batch value, an update side mutex when updating ->high and ->batch, and use ACCESS_ONCE() for ->batch users that expect a stable value. 2: avoid draining pages in zone_pcp_update(), rely upon the memory barriers added to fix #1 3: factor out quite a few functions, and then call the appropriate one. Note that it results in a change to the behavior of zone_pcp_update(), which is used by memory_hotplug. I'm rather certain that I've diserned (and preserved) the essential behavior (changing ->high and ->batch), and only eliminated unneeded actions (draining the per cpu pages), but this may not be the case. Further note that the draining of pages that previously took place in zone_pcp_update() occured after repeated draining when attempting to offline a page, and after the offline has "succeeded". It appears that the draining was added to zone_pcp_update() to avoid refactoring setup_pageset() into 2 funtions. This patch: Creates pageset_set_batch() for use in setup_pageset(). pageset_set_batch() imitates the functionality of setup_pagelist_highmark(), but uses the boot time (percpu_pagelist_fraction == 0) calculations for determining ->high based on ->batch. Signed-off-by:
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Libin authored
(*->vm_end - *->vm_start) >> PAGE_SHIFT operation is implemented as a inline funcion vma_pages() in linux/mm.h, so using it. Signed-off-by:
Libin <huawei.libin@huawei.com> Signed-off-by:
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Libin authored
(*->vm_end - *->vm_start) >> PAGE_SHIFT operation is implemented as a inline funcion vma_pages() in linux/mm.h, so using it. Signed-off-by:
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Libin authored
(*->vm_end - *->vm_start) >> PAGE_SHIFT operation is implemented as a inline funcion vma_pages() in linux/mm.h, so using it. Signed-off-by:
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Minchan Kim authored
Swap subsystem does lazy swap slot free with expecting the page would be swapped out again so we can avoid unnecessary write. But the problem in in-memory swap(ex, zram) is that it consumes memory space until vm_swap_full(ie, used half of all of swap device) condition meet. It could be bad if we use multiple swap device, small in-memory swap and big storage swap or in-memory swap alone. This patch makes swap subsystem free swap slot as soon as swap-read is completed and make the swapcache page dirty so the page should be written out the swap device to reclaim it. It means we never lose it. I tested this patch with kernel compile workload. 1. before compile time : 9882.42 zram max wasted space by fragmentation: 13471881 byte memory space consumed by zram: 174227456 byte the number of slot free notify: 206684 2. after compile time : 9653.90 zram max wasted space by fragmentation: 11805932 byte memory space consumed by zram: 154001408 byte the number of slot free notify: 426972 [akpm@linux-foundation.org: tweak comment text] [artem.savkov@gmail.com: fix BUG due to non-swapcache pages in end_swap_bio_read()] [akpm@linux-foundation.org: invert unlikely() test, augment comment, 80-col cleanup] Signed-off-by:
Dan Magenheimer <dan.magenheimer@oracle.com> Signed-off-by:
Minchan Kim <minchan@kernel.org> Signed-off-by:
Artem Savkov <artem.savkov@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Konrad Rzeszutek Wilk <konrad@darnok.org> Cc: Shaohua Li <shli@kernel.org> Signed-off-by:
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David Rientjes authored
For processes that have detached their mm's, task_in_mem_cgroup() unnecessarily takes task_lock() when rcu_read_lock() is all that is necessary to call mem_cgroup_from_task(). While we're here, switch task_in_mem_cgroup() to return bool. Signed-off-by:
David Rientjes <rientjes@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by:
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Pavel Emelyanov authored
In order to reuse bits from pagemap entries gracefully, we leave the entries as is but on pagemap open emit a warning in dmesg, that bits 55-60 are about to change in a couple of releases. Next, if a user issues soft-dirty clear command via the clear_refs file (it was disabled before v3.9) we assume that he's aware of the new pagemap format, note that fact and report the bits in pagemap in the new manner. The "migration strategy" looks like this then: 1. existing users are not affected -- they don't touch soft-dirty feature, thus see old bits in pagemap, but are warned and have time to fix themselves 2. those who use soft-dirty know about new pagemap format 3. some time soon we get rid of any signs of page-shift in pagemap as well as this trick with clear-soft-dirty affecting pagemap format. Signed-off-by:
Pavel Emelyanov <xemul@parallels.com> Cc: Matt Mackall <mpm@selenic.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by:
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Pavel Emelyanov authored
The soft-dirty is a bit on a PTE which helps to track which pages a task writes to. In order to do this tracking one should 1. Clear soft-dirty bits from PTEs ("echo 4 > /proc/PID/clear_refs) 2. Wait some time. 3. Read soft-dirty bits (55'th in /proc/PID/pagemap2 entries) To do this tracking, the writable bit is cleared from PTEs when the soft-dirty bit is. Thus, after this, when the task tries to modify a page at some virtual address the #PF occurs and the kernel sets the soft-dirty bit on the respective PTE. Note, that although all the task's address space is marked as r/o after the soft-dirty bits clear, the #PF-s that occur after that are processed fast. This is so, since the pages are still mapped to physical memory, and thus all the kernel does is finds this fact out and puts back writable, dirty and soft-dirty bits on the PTE. Another thing to note, is that when mremap moves PTEs they are marked with soft-dirty as well, since from the user perspective mremap modifies the virtual memory at mremap's new address. Signed-off-by: -
Pavel Emelyanov authored
These bits are always constant (== PAGE_SHIFT) and just occupy space in the entry. Moreover, in next patch we will need to report one more bit in the pagemap, but all bits are already busy on it. That said, describe the pagemap entry that has 6 more free zero bits. Signed-off-by:
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Pavel Emelyanov authored
In the next patch the clear-refs-type will be required in clear_refs_pte_range funciton, so prepare the walk->private to carry this info. Signed-off-by:
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Pavel Emelyanov authored
This is the implementation of the soft-dirty bit concept that should help keep track of changes in user memory, which in turn is very-very required by the checkpoint-restore project (http://criu.org). To create a dump of an application(s) we save all the information about it to files, and the biggest part of such dump is the contents of tasks' memory. However, there are usage scenarios where it's not required to get _all_ the task memory while creating a dump. For example, when doing periodical dumps, it's only required to take full memory dump only at the first step and then take incremental changes of memory. Another example is live migration. We copy all the memory to the destination node without stopping all tasks, then stop them, check for what pages has changed, dump it and the rest of the state, then copy it to the destination node. This decreases freeze time significantly. That said, some help from kernel to watch how processes modify the contents of their memory is required. The proposal is to track changes with the help of new soft-dirty bit this way: 1. First do "echo 4 > /proc/$pid/clear_refs". At that point kernel clears the soft dirty _and_ the writable bits from all ptes of process $pid. From now on every write to any page will result in #pf and the subsequent call to pte_mkdirty/pmd_mkdirty, which in turn will set the soft dirty flag. 2. Then read the /proc/$pid/pagemap2 and check the soft-dirty bit reported there (the 55'th one). If set, the respective pte was written to since last call to clear refs. The soft-dirty bit is the _PAGE_BIT_HIDDEN one. Although it's used by kmemcheck, the latter one marks kernel pages with it, while the former bit is put on user pages so they do not conflict to each other. This patch: A new clear-refs type will be added in the next patch, so prepare code for that. [akpm@linux-foundation.org: don't assume that sizeof(enum clear_refs_types) == sizeof(int)] Signed-off-by:
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Kees Cook authored
The template lookup interface does not provide a way to use format strings, so make sure that the interface cannot be abused accidentally. Signed-off-by:
Kees Cook <keescook@chromium.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: <stable@vger.kernel.org> Signed-off-by:
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Kees Cook authored
Disk names may contain arbitrary strings, so they must not be interpreted as format strings. It seems that only md allows arbitrary strings to be used for disk names, but this could allow for a local memory corruption from uid 0 into ring 0. CVE-2013-2851 Signed-off-by:
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Jonathan Salwan authored
In drivers/cdrom/cdrom.c mmc_ioctl_cdrom_read_data() allocates a memory area with kmalloc in line 2885. 2885 cgc->buffer = kmalloc(blocksize, GFP_KERNEL); 2886 if (cgc->buffer == NULL) 2887 return -ENOMEM; In line 2908 we can find the copy_to_user function: 2908 if (!ret && copy_to_user(arg, cgc->buffer, blocksize)) The cgc->buffer is never cleaned and initialized before this function. If ret = 0 with the previous basic block, it's possible to display some memory bytes in kernel space from userspace. When we read a block from the disk it normally fills the ->buffer but if the drive is malfunctioning there is a chance that it would only be partially filled. The result is an leak information to userspace. Signed-off-by:
Dan Carpenter <dan.carpenter@oracle.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by:
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Cong Wang authored
There is a hole in struct hd_geometry, so we have to zero the struct on stack before copying it to user-space. Signed-off-by:
Cong Wang <amwang@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by:
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Libo Chen authored
Without this patch, gdrom_major will leak when gd.cd_info alloc fails. Signed-off-by:
Libo Chen <libo.chen@huawei.com> Cc: Jens Axboe <axboe@kernel.dk> Acked-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
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Xue jiufei authored
There may exist NULL pointer dereference in config_item_name() when one volume (say Volume A) unmounts while another (say Volume B) mounting. Volume A Volume B already Mounted. Unmounting, call o2hb_heartbeat_group_drop_item() -> config_item_put(item) set reg(A)->item.ci_name to NULL in function config_item_cleanup(). begin mounting, call o2hb_region_pin() and tranverse all regions. When reading reg(A)->item.ci_name, it causes NULL pointer dereference. call o2hb_region_release() and del reg(A) from list. So we should skip accessing regions that is going to release when tranverse o2hb_all_regions. Signed-off-by:Yiwen Jiang <jiangyiwen@huawei.com> Signed-off-by:
joyce <xuejiufei@huawei.com> Acked-by:
Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Sunil Mushran <sunil.mushran@gmail.com> Cc: Jie Liu <jeff.liu@oracle.com> Signed-off-by:
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Jie Liu authored
Adjust switch..case syntax at o2net_state_change to meet the kernel coding standard. s/printk/pr_info/. [akpm@linux-foundation.org: revert pr_foo() change] Signed-off-by:
Jie Liu <jeff.liu@oracle.com> Acked-by:
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Jie Liu authored
Fix a comment typo in o2quo_hb_still_up() Signed-off-by:
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Jie Liu authored
s/o2hb_global_hearbeat_mode_set/o2hb_global_heartbeat_mode_set/ to make the signature of those routines in a consistent manner with others for heartbeating. Signed-off-by:
Sunil Mushran <sunil.mushran@gmail.com> Cc: Gurudas Pai <gurudas.pai@oracle.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Noboru Iwamatsu <n_iwamatsu@jp.fujitsu.com> Cc: Srinivas Eeeda <srinivas.eeda@oracle.com> Cc: Tao Ma <tm@tao.ma> Signed-off-by:
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Noboru Iwamatsu authored
Under heavy I/O load, writing the disk heartbeat can be forced to wait for minutes, and this causes the node to be fenced. This patch tries to use WRITE_SYNC in submitting the heartbeat bio, so that writing the heartbeat will have a priority over other requests. Signed-off-by:
Noboru Iwamatsu <n_iwamatsu@jp.fujitsu.com> Acked-by:
Tao Ma <tm@tao.ma> Acked-by:
Gurudas Pai <gurudas.pai@oracle.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Signed-off-by:
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Junxiao Bi authored
Inlined xattr shared free space of inode block with inlined data or data extent record, so the size of the later two should be adjusted when inlined xattr is enabled. See ocfs2_xattr_ibody_init(). But this isn't done well when reflink. For inode with inlined data, its max inlined data size is adjusted in ocfs2_duplicate_inline_data(), no problem. But for inode with data extent record, its record count isn't adjusted. Fix it, or data extent record and inlined xattr may overwrite each other, then cause data corruption or xattr failure. One panic caused by this bug in our test environment is the following: kernel BUG at fs/ocfs2/xattr.c:1435! invalid opcode: 0000 [#1] SMP Pid: 10871, comm: multi_reflink_t Not tainted 2.6.39-300.17.1.el5uek #1 RIP: ocfs2_xa_offset_pointer+0x17/0x20 [ocfs2] RSP: e02b:ffff88007a587948 EFLAGS: 00010283 RAX: 0000000000000000 RBX: 0000000000000010 RCX: 00000000000051e4 RDX: ffff880057092060 RSI: 0000000000000f80 RDI: ffff88007a587a68 RBP: ffff88007a587948 R08: 00000000000062f4 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000010 R13: ffff88007a587a68 R14: 0000000000000001 R15: ffff88007a587c68 FS: 00007fccff7f06e0(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000 CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000015cf000 CR3: 000000007aa76000 CR4: 0000000000000660 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process multi_reflink_t Call Trace: ocfs2_xa_reuse_entry+0x60/0x280 [ocfs2] ocfs2_xa_prepare_entry+0x17e/0x2a0 [ocfs2] ocfs2_xa_set+0xcc/0x250 [ocfs2] ocfs2_xattr_ibody_set+0x98/0x230 [ocfs2] __ocfs2_xattr_set_handle+0x4f/0x700 [ocfs2] ocfs2_xattr_set+0x6c6/0x890 [ocfs2] ocfs2_xattr_user_set+0x46/0x50 [ocfs2] generic_setxattr+0x70/0x90 __vfs_setxattr_noperm+0x80/0x1a0 vfs_setxattr+0xa9/0xb0 setxattr+0xc3/0x120 sys_fsetxattr+0xa8/0xd0 system_call_fastpath+0x16/0x1b Signed-off-by:Junxiao Bi <junxiao.bi@oracle.com> Reviewed-by:
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Younger Liu authored
While deleting a file with ocfs2_unlink(), there is a bug in this function. This bug will result in filesystem read-only. After calling ocfs2_orphan_add(), the file which will be deleted is added into orphan dir. If ocfs2_delete_entry() fails, the file still exists in the parent dir. And this scenario introduces a conflict of metadata. If a file is added into orphan dir, when we put inode of the file with iput(), the inode i_flags is setted (~OCFS2_VALID_FL) in ocfs2_remove_inode(), and then write back to disk. But as previously mentioned, the file still exists in the parent dir. On other nodes, the file can be still accessed. When first read the file with ocfs2_read_blocks() from disk, It will check and avalidate inode using ocfs2_validate_inode_block(). So File system will be readonly because the inode is invalid. In other words, the inode i_flags has been set (~OCFS2_VALID_FL). [akpm@linux-foundation.org: cleanups] [jeff.liu@oracle.com: s/inode_is_unlinkable/ocfs2_inode_is_unlinkable/] Signed-off-by:
Younger Liu <younger.liu@huawei.com> Signed-off-by:
Jensen <shencanquan@huawei.com> Cc: Jie Liu <jeff.liu@oracle.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Sunil Mushran <sunil.mushran@gmail.com> Signed-off-by:
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