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2013-10-09sched/numa: Remove check that skips small VMAsMel Gorman1-4/+0
task_numa_work skips small VMAs. At the time the logic was to reduce the scanning overhead which was considerable. It is a dubious hack at best. It would make much more sense to cache where faults have been observed and only rescan those regions during subsequent PTE scans. Remove this hack as motivation to do it properly in the future. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-29-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09mm: numa: Scan pages with elevated page_mapcountMel Gorman5-29/+18
Currently automatic NUMA balancing is unable to distinguish between false shared versus private pages except by ignoring pages with an elevated page_mapcount entirely. This avoids shared pages bouncing between the nodes whose task is using them but that is ignored quite a lot of data. This patch kicks away the training wheels in preparation for adding support for identifying shared/private pages is now in place. The ordering is so that the impact of the shared/private detection can be easily measured. Note that the patch does not migrate shared, file-backed within vmas marked VM_EXEC as these are generally shared library pages. Migrating such pages is not beneficial as there is an expectation they are read-shared between caches and iTLB and iCache pressure is generally low. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-28-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Check current->mm before allocating NUMA faultsMel Gorman1-2/+4
task_numa_placement checks current->mm but after buffers for faults have already been uselessly allocated. Move the check earlier. [peterz@infradead.org: Identified the problem] Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-27-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Add infrastructure for split shared/private accounting of NUMA ↵Mel Gorman4-17/+47
hinting faults Ideally it would be possible to distinguish between NUMA hinting faults that are private to a task and those that are shared. This patch prepares infrastructure for separately accounting shared and private faults by allocating the necessary buffers and passing in relevant information. For now, all faults are treated as private and detection will be introduced later. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-26-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Reschedule task on preferred NUMA node once selectedMel Gorman3-1/+65
A preferred node is selected based on the node the most NUMA hinting faults was incurred on. There is no guarantee that the task is running on that node at the time so this patch rescheules the task to run on the most idle CPU of the selected node when selected. This avoids waiting for the balancer to make a decision. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-25-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Resist moving tasks towards nodes with fewer hinting faultsMel Gorman2-0/+41
Just as "sched: Favour moving tasks towards the preferred node" favours moving tasks towards nodes with a higher number of recorded NUMA hinting faults, this patch resists moving tasks towards nodes with lower faults. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-24-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Favour moving tasks towards the preferred nodeMel Gorman6-6/+83
This patch favours moving tasks towards NUMA node that recorded a higher number of NUMA faults during active load balancing. Ideally this is self-reinforcing as the longer the task runs on that node, the more faults it should incur causing task_numa_placement to keep the task running on that node. In reality a big weakness is that the nodes CPUs can be overloaded and it would be more efficient to queue tasks on an idle node and migrate to the new node. This would require additional smarts in the balancer so for now the balancer will simply prefer to place the task on the preferred node for a PTE scans which is controlled by the numa_balancing_settle_count sysctl. Once the settle_count number of scans has complete the schedule is free to place the task on an alternative node if the load is imbalanced. [srikar@linux.vnet.ibm.com: Fixed statistics] Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> [ Tunable and use higher faults instead of preferred. ] Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-23-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Update NUMA hinting faults once per scanMel Gorman3-3/+27
NUMA hinting fault counts and placement decisions are both recorded in the same array which distorts the samples in an unpredictable fashion. The values linearly accumulate during the scan and then decay creating a sawtooth-like pattern in the per-node counts. It also means that placement decisions are time sensitive. At best it means that it is very difficult to state that the buffer holds a decaying average of past faulting behaviour. At worst, it can confuse the load balancer if it sees one node with an artifically high count due to very recent faulting activity and may create a bouncing effect. This patch adds a second array. numa_faults stores the historical data which is used for placement decisions. numa_faults_buffer holds the fault activity during the current scan window. When the scan completes, numa_faults decays and the values from numa_faults_buffer are copied across. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-22-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Select a preferred node with the most numa hinting faultsMel Gorman3-2/+17
This patch selects a preferred node for a task to run on based on the NUMA hinting faults. This information is later used to migrate tasks towards the node during balancing. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-21-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Track NUMA hinting faults on per-node basisMel Gorman4-1/+27
This patch tracks what nodes numa hinting faults were incurred on. This information is later used to schedule a task on the node storing the pages most frequently faulted by the task. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-20-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Slow scan rate if no NUMA hinting faults are being recordedMel Gorman1-0/+12
NUMA PTE scanning slows if a NUMA hinting fault was trapped and no page was migrated. For long-lived but idle processes there may be no faults but the scan rate will be high and just waste CPU. This patch will slow the scan rate for processes that are not trapping faults. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-19-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Set the scan rate proportional to the memory usage of the task ↵Mel Gorman3-17/+83
being scanned The NUMA PTE scan rate is controlled with a combination of the numa_balancing_scan_period_min, numa_balancing_scan_period_max and numa_balancing_scan_size. This scan rate is independent of the size of the task and as an aside it is further complicated by the fact that numa_balancing_scan_size controls how many pages are marked pte_numa and not how much virtual memory is scanned. In combination, it is almost impossible to meaningfully tune the min and max scan periods and reasoning about performance is complex when the time to complete a full scan is is partially a function of the tasks memory size. This patch alters the semantic of the min and max tunables to be about tuning the length time it takes to complete a scan of a tasks occupied virtual address space. Conceptually this is a lot easier to understand. There is a "sanity" check to ensure the scan rate is never extremely fast based on the amount of virtual memory that should be scanned in a second. The default of 2.5G seems arbitrary but it is to have the maximum scan rate after the patch roughly match the maximum scan rate before the patch was applied. On a similar note, numa_scan_period is in milliseconds and not jiffies. Properly placed pages slow the scanning rate but adding 10 jiffies to numa_scan_period means that the rate scanning slows depends on HZ which is confusing. Get rid of the jiffies_to_msec conversion and treat it as ms. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-18-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Initialise numa_next_scan properlyMel Gorman2-2/+9
Scan delay logic and resets are currently initialised to start scanning immediately instead of delaying properly. Initialise them properly at fork time and catch when a new mm has been allocated. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-17-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09Revert "mm: sched: numa: Delay PTE scanning until a task is scheduled on a ↵Mel Gorman4-34/+1
new node" PTE scanning and NUMA hinting fault handling is expensive so commit 5bca2303 ("mm: sched: numa: Delay PTE scanning until a task is scheduled on a new node") deferred the PTE scan until a task had been scheduled on another node. The problem is that in the purely shared memory case that this may never happen and no NUMA hinting fault information will be captured. We are not ruling out the possibility that something better can be done here but for now, this patch needs to be reverted and depend entirely on the scan_delay to avoid punishing short-lived processes. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-16-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Continue PTE scanning even if migrate rate limitedPeter Zijlstra1-8/+0
Avoiding marking PTEs pte_numa because a particular NUMA node is migrate rate limited sees like a bad idea. Even if this node can't migrate anymore other nodes might and we want up-to-date information to do balance decisions. We already rate limit the actual migrations, this should leave enough bandwidth to allow the non-migrating scanning. I think its important we keep up-to-date information if we're going to do placement based on it. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1381141781-10992-15-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Mitigate chance that same task always updates PTEsPeter Zijlstra1-1/+7
With a trace_printk("working\n"); right after the cmpxchg in task_numa_work() we can see that of a 4 thread process, its always the same task winning the race and doing the protection change. This is a problem since the task doing the protection change has a penalty for taking faults -- it is busy when marking the PTEs. If its always the same task the ->numa_faults[] get severely skewed. Avoid this by delaying the task doing the protection change such that it is unlikely to win the privilege again. Before: root@interlagos:~# grep "thread 0/.*working" /debug/tracing/trace | tail -15 thread 0/0-3232 [022] .... 212.787402: task_numa_work: working thread 0/0-3232 [022] .... 212.888473: task_numa_work: working thread 0/0-3232 [022] .... 212.989538: task_numa_work: working thread 0/0-3232 [022] .... 213.090602: task_numa_work: working thread 0/0-3232 [022] .... 213.191667: task_numa_work: working thread 0/0-3232 [022] .... 213.292734: task_numa_work: working thread 0/0-3232 [022] .... 213.393804: task_numa_work: working thread 0/0-3232 [022] .... 213.494869: task_numa_work: working thread 0/0-3232 [022] .... 213.596937: task_numa_work: working thread 0/0-3232 [022] .... 213.699000: task_numa_work: working thread 0/0-3232 [022] .... 213.801067: task_numa_work: working thread 0/0-3232 [022] .... 213.903155: task_numa_work: working thread 0/0-3232 [022] .... 214.005201: task_numa_work: working thread 0/0-3232 [022] .... 214.107266: task_numa_work: working thread 0/0-3232 [022] .... 214.209342: task_numa_work: working After: root@interlagos:~# grep "thread 0/.*working" /debug/tracing/trace | tail -15 thread 0/0-3253 [005] .... 136.865051: task_numa_work: working thread 0/2-3255 [026] .... 136.965134: task_numa_work: working thread 0/3-3256 [024] .... 137.065217: task_numa_work: working thread 0/3-3256 [024] .... 137.165302: task_numa_work: working thread 0/3-3256 [024] .... 137.265382: task_numa_work: working thread 0/0-3253 [004] .... 137.366465: task_numa_work: working thread 0/2-3255 [026] .... 137.466549: task_numa_work: working thread 0/0-3253 [004] .... 137.566629: task_numa_work: working thread 0/0-3253 [004] .... 137.666711: task_numa_work: working thread 0/1-3254 [028] .... 137.766799: task_numa_work: working thread 0/0-3253 [004] .... 137.866876: task_numa_work: working thread 0/2-3255 [026] .... 137.966960: task_numa_work: working thread 0/1-3254 [028] .... 138.067041: task_numa_work: working thread 0/2-3255 [026] .... 138.167123: task_numa_work: working thread 0/3-3256 [024] .... 138.267207: task_numa_work: working Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1381141781-10992-14-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09mm: numa: Do not migrate or account for hinting faults on the zero pageMel Gorman2-1/+10
The zero page is not replicated between nodes and is often shared between processes. The data is read-only and likely to be cached in local CPUs if heavily accessed meaning that the remote memory access cost is less of a concern. This patch prevents trapping faults on the zero pages. For tasks using the zero page this will reduce the number of PTE updates, TLB flushes and hinting faults. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> [ Correct use of is_huge_zero_page] Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-13-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09mm: Only flush TLBs if a transhuge PMD is modified for NUMA pte scanningMel Gorman2-7/+26
NUMA PTE scanning is expensive both in terms of the scanning itself and the TLB flush if there are any updates. The TLB flush is avoided if no PTEs are updated but there is a bug where transhuge PMDs are considered to be updated even if they were already pmd_numa. This patch addresses the problem and TLB flushes should be reduced. Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-12-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09mm: Do not flush TLB during protection change if !pte_present && ↵Mel Gorman1-1/+2
!migration_entry NUMA PTE scanning is expensive both in terms of the scanning itself and the TLB flush if there are any updates. Currently non-present PTEs are accounted for as an update and incurring a TLB flush where it is only necessary for anonymous migration entries. This patch addresses the problem and should reduce TLB flushes. Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-11-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09mm: Account for a THP NUMA hinting update as one PTE updateMel Gorman1-1/+1
A THP PMD update is accounted for as 512 pages updated in vmstat. This is large difference when estimating the cost of automatic NUMA balancing and can be misleading when comparing results that had collapsed versus split THP. This patch addresses the accounting issue. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-10-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09mm: Close races between THP migration and PMD numa clearingMel Gorman2-26/+26
THP migration uses the page lock to guard against parallel allocations but there are cases like this still open Task A Task B --------------------- --------------------- do_huge_pmd_numa_page do_huge_pmd_numa_page lock_page mpol_misplaced == -1 unlock_page goto clear_pmdnuma lock_page mpol_misplaced == 2 migrate_misplaced_transhuge pmd = pmd_mknonnuma set_pmd_at During hours of testing, one crashed with weird errors and while I have no direct evidence, I suspect something like the race above happened. This patch extends the page lock to being held until the pmd_numa is cleared to prevent migration starting in parallel while the pmd_numa is being cleared. It also flushes the old pmd entry and orders pagetable insertion before rmap insertion. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-9-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09mm: numa: Sanitize task_numa_fault() callsitesMel Gorman2-44/+34
There are three callers of task_numa_fault(): - do_huge_pmd_numa_page(): Accounts against the current node, not the node where the page resides, unless we migrated, in which case it accounts against the node we migrated to. - do_numa_page(): Accounts against the current node, not the node where the page resides, unless we migrated, in which case it accounts against the node we migrated to. - do_pmd_numa_page(): Accounts not at all when the page isn't migrated, otherwise accounts against the node we migrated towards. This seems wrong to me; all three sites should have the same sementaics, furthermore we should accounts against where the page really is, we already know where the task is. So modify all three sites to always account; we did after all receive the fault; and always account to where the page is after migration, regardless of success. They all still differ on when they clear the PTE/PMD; ideally that would get sorted too. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-8-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09mm: Prevent parallel splits during THP migrationMel Gorman1-14/+30
THP migrations are serialised by the page lock but on its own that does not prevent THP splits. If the page is split during THP migration then the pmd_same checks will prevent page table corruption but the unlock page and other fix-ups potentially will cause corruption. This patch takes the anon_vma lock to prevent parallel splits during migration. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-7-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09mm: Wait for THP migrations to complete during NUMA hinting faultsMel Gorman1-7/+16
The locking for migrating THP is unusual. While normal page migration prevents parallel accesses using a migration PTE, THP migration relies on a combination of the page_table_lock, the page lock and the existance of the NUMA hinting PTE to guarantee safety but there is a bug in the scheme. If a THP page is currently being migrated and another thread traps a fault on the same page it checks if the page is misplaced. If it is not, then pmd_numa is cleared. The problem is that it checks if the page is misplaced without holding the page lock meaning that the racing thread can be migrating the THP when the second thread clears the NUMA bit and faults a stale page. This patch checks if the page is potentially being migrated and stalls using the lock_page if it is potentially being migrated before checking if the page is misplaced or not. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-6-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09mm: numa: Do not account for a hinting fault if we racedMel Gorman1-1/+4
If another task handled a hinting fault in parallel then do not double account for it. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-5-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09sched/numa: Fix commentsPeter Zijlstra2-5/+5
Fix a 80 column violation and a PTE vs PMD reference. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1381141781-10992-4-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09mm: numa: Document automatic NUMA balancing sysctlsMel Gorman1-0/+66
Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-3-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09Merge tag 'v3.12-rc4' into sched/coreIngo Molnar893-4829/+8754
Merge Linux v3.12-rc4 to fix a conflict and also to refresh the tree before applying more scheduler patches. Conflicts: arch/avr32/include/asm/Kbuild Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-07Linux 3.12-rc4Linus Torvalds1-1/+1
2013-10-07net: Update the sysctl permissions handler to test effective uid/gidEric W. Biederman1-2/+2
Modify the code to use current_euid(), and in_egroup_p, as in done in fs/proc/proc_sysctl.c:test_perm() Cc: stable@vger.kernel.org Reviewed-by: Eric Sandeen <sandeen@redhat.com> Reported-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-10-07Merge git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pendingLinus Torvalds8-25/+67
Pull SCSI target fixes from Nicholas Bellinger: "Here are the outstanding target fixes queued up for v3.12-rc4 code. The highlights include: - Make vhost/scsi tag percpu_ida_alloc() use GFP_ATOMIC - Allow sess_cmd_map allocation failure fallback to use vzalloc - Fix COMPARE_AND_WRITE se_cmd->data_length bug with FILEIO backends - Fixes for COMPARE_AND_WRITE callback recursive failure OOPs + non zero scsi_status bug - Make iscsi-target do acknowledgement tag release from RX context - Setup iscsi-target with extra (cmdsn_depth / 2) percpu_ida tags Also included is a iscsi-target patch CC'ed for v3.10+ that avoids legacy wait_for_task=true release during fast-past StatSN acknowledgement, and two other SRP target related patches that address long-standing issues that are CC'ed for v3.3+. Extra thanks to Thomas Glanzmann for his testing feedback with COMPARE_AND_WRITE + EXTENDED_COPY VAAI logic" * git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: iscsi-target; Allow an extra tag_num / 2 number of percpu_ida tags iscsi-target: Perform release of acknowledged tags from RX context iscsi-target: Only perform wait_for_tasks when performing shutdown target: Fail on non zero scsi_status in compare_and_write_callback target: Fix recursive COMPARE_AND_WRITE callback failure target: Reset data_length for COMPARE_AND_WRITE to NoLB * block_size ib_srpt: always set response for task management target: Fall back to vzalloc upon ->sess_cmd_map kzalloc failure vhost/scsi: Use GFP_ATOMIC with percpu_ida_alloc for obtaining tag ib_srpt: Destroy cm_id before destroying QP. target: Fix xop->dbl assignment in target_xcopy_parse_segdesc_02
2013-10-07Merge branch 'fixes' of git://git.infradead.org/users/vkoul/slave-dmaLinus Torvalds3-17/+17
Pull slave-dmaengine fixes from Vinod Koul: "Here is the slave dmanegine fixes. We have the fix for deadlock issue on imx-dma by Michael and Josh's edma config fix along with author change" * 'fixes' of git://git.infradead.org/users/vkoul/slave-dma: dmaengine: imx-dma: fix callback path in tasklet dmaengine: imx-dma: fix lockdep issue between irqhandler and tasklet dmaengine: imx-dma: fix slow path issue in prep_dma_cyclic dma/Kconfig: Make TI_EDMA select TI_PRIV_EDMA edma: Update author email address
2013-10-06sched/rt: Remove redundant nr_cpus_allowed testShawn Bohrer1-2/+1
In 76854c7e8f3f4172fef091e78d88b3b751463ac6 ("sched: Use rt.nr_cpus_allowed to recover select_task_rq() cycles") an optimization was added to select_task_rq_rt() that immediately returns when p->nr_cpus_allowed == 1 at the beginning of the function. This makes the latter p->nr_cpus_allowed > 1 check redundant, which can now be removed. Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: Mike Galbraith <mgalbraith@suse.de> Cc: tomk@rgmadvisors.com Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1380914693-24634-1-git-send-email-shawn.bohrer@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-05Merge branch 'for-linus' of ↵Linus Torvalds6-17/+39
git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs Pull btrfs fixes from Chris Mason: "This is a small collection of fixes, including a regression fix from Liu Bo that solves rare crashes with compression on. I've merged my for-linus up to 3.12-rc3 because the top commit is only meant for 3.12. The rest of the fixes are also available in my master branch on top of my last 3.11 based pull" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: btrfs: Fix crash due to not allocating integrity data for a bioset Btrfs: fix a use-after-free bug in btrfs_dev_replace_finishing Btrfs: eliminate races in worker stopping code Btrfs: fix crash of compressed writes Btrfs: fix transid verify errors when recovering log tree
2013-10-05Merge tag 'gpio-v3.12-2' of ↵Linus Torvalds1-57/+101
git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio Pull GPIO fixes from Linus Walleij: "Two patches for the OMAP driver, dealing with setting up IRQs properly on the device tree boot path" * tag 'gpio-v3.12-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: gpio/omap: auto-setup a GPIO when used as an IRQ gpio/omap: maintain GPIO and IRQ usage separately
2013-10-05Merge tag 'usb-3.12-rc4' of ↵Linus Torvalds8-13/+29
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb Pull USB fixes from Greg KH: "Here are none fixes for various USB driver problems. The majority are gadget/musb fixes, but there are some new device ids in here as well" * tag 'usb-3.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: usb: chipidea: add Intel Clovertrail pci id usb: gadget: s3c-hsotg: fix can_write limit for non-periodic endpoints usb: gadget: f_fs: fix error handling usb: musb: dsps: do not bind to "musb-hdrc" USB: serial: option: Ignore card reader interface on Huawei E1750 usb: musb: gadget: fix otg active status flag usb: phy: gpio-vbus: fix deferred probe from __init usb: gadget: pxa25x_udc: fix deferred probe from __init usb: musb: fix otg default state
2013-10-05Merge tag 'tty-3.12-rc4' of ↵Linus Torvalds2-20/+27
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty fixes from Greg KH: "Here are two tty driver fixes for 3.12-rc4. One fixes the reported regression in the n_tty code that a number of people found recently, and the other one fixes an issue with xen consoles that broke in 3.10" * tag 'tty-3.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: xen/hvc: allow xenboot console to be used again tty: Fix pty master read() after slave closes
2013-10-05Merge tag 'staging-3.12-rc4' of ↵Linus Torvalds4-28/+21
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging Pull staging fixes from Greg KH: "Here are 4 tiny staging and iio driver fixes for 3.12-rc4. Nothing major, just some small fixes for reported issues" * tag 'staging-3.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: staging: comedi: ni_65xx: (bug fix) confine insn_bits to one subdevice iio:magnetometer: Bugfix magnetometer default output registers iio: Remove debugfs entries in iio_device_unregister() iio: amplifiers: ad8366: Remove regulator_put
2013-10-05btrfs: Fix crash due to not allocating integrity data for a biosetDarrick J. Wong1-0/+8
When btrfs creates a bioset, we must also allocate the integrity data pool. Otherwise btrfs will crash when it tries to submit a bio to a checksumming disk: BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 IP: [<ffffffff8111e28a>] mempool_alloc+0x4a/0x150 PGD 2305e4067 PUD 23063d067 PMD 0 Oops: 0000 [#1] PREEMPT SMP Modules linked in: btrfs scsi_debug xfs ext4 jbd2 ext3 jbd mbcache sch_fq_codel eeprom lpc_ich mfd_core nfsd exportfs auth_rpcgss af_packet raid6_pq xor zlib_deflate libcrc32c [last unloaded: scsi_debug] CPU: 1 PID: 4486 Comm: mount Not tainted 3.12.0-rc1-mcsum #2 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 task: ffff8802451c9720 ti: ffff880230698000 task.ti: ffff880230698000 RIP: 0010:[<ffffffff8111e28a>] [<ffffffff8111e28a>] mempool_alloc+0x4a/0x150 RSP: 0018:ffff880230699688 EFLAGS: 00010286 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 00000000005f8445 RDX: 0000000000000001 RSI: 0000000000000010 RDI: 0000000000000000 RBP: ffff8802306996f8 R08: 0000000000011200 R09: 0000000000000008 R10: 0000000000000020 R11: ffff88009d6e8000 R12: 0000000000011210 R13: 0000000000000030 R14: ffff8802306996b8 R15: ffff8802451c9720 FS: 00007f25b8a16800(0000) GS:ffff88024fc80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000018 CR3: 0000000230576000 CR4: 00000000000007e0 Stack: ffff8802451c9720 0000000000000002 ffffffff81a97100 0000000000281250 ffffffff81a96480 ffff88024fc99150 ffff880228d18200 0000000000000000 0000000000000000 0000000000000040 ffff880230e8c2e8 ffff8802459dc900 Call Trace: [<ffffffff811b2208>] bio_integrity_alloc+0x48/0x1b0 [<ffffffff811b26fc>] bio_integrity_prep+0xac/0x360 [<ffffffff8111e298>] ? mempool_alloc+0x58/0x150 [<ffffffffa03e8041>] ? alloc_extent_state+0x31/0x110 [btrfs] [<ffffffff81241579>] blk_queue_bio+0x1c9/0x460 [<ffffffff8123e58a>] generic_make_request+0xca/0x100 [<ffffffff8123e639>] submit_bio+0x79/0x160 [<ffffffffa03f865e>] btrfs_map_bio+0x48e/0x5b0 [btrfs] [<ffffffffa03c821a>] btree_submit_bio_hook+0xda/0x110 [btrfs] [<ffffffffa03e7eba>] submit_one_bio+0x6a/0xa0 [btrfs] [<ffffffffa03ef450>] read_extent_buffer_pages+0x250/0x310 [btrfs] [<ffffffff8125eef6>] ? __radix_tree_preload+0x66/0xf0 [<ffffffff8125f1c5>] ? radix_tree_insert+0x95/0x260 [<ffffffffa03c66f6>] btree_read_extent_buffer_pages.constprop.128+0xb6/0x120 [btrfs] [<ffffffffa03c8c1a>] read_tree_block+0x3a/0x60 [btrfs] [<ffffffffa03caefd>] open_ctree+0x139d/0x2030 [btrfs] [<ffffffffa03a282a>] btrfs_mount+0x53a/0x7d0 [btrfs] [<ffffffff8113ab0b>] ? pcpu_alloc+0x8eb/0x9f0 [<ffffffff81167305>] ? __kmalloc_track_caller+0x35/0x1e0 [<ffffffff81176ba0>] mount_fs+0x20/0xd0 [<ffffffff81191096>] vfs_kern_mount+0x76/0x120 [<ffffffff81193320>] do_mount+0x200/0xa40 [<ffffffff81135cdb>] ? strndup_user+0x5b/0x80 [<ffffffff81193bf0>] SyS_mount+0x90/0xe0 [<ffffffff8156d31d>] system_call_fastpath+0x1a/0x1f Code: 4c 8d 75 a8 4c 89 6d e8 45 89 e0 4c 8d 6f 30 48 89 5d d8 41 83 e0 af 48 89 fb 49 83 c6 18 4c 89 7d f8 65 4c 8b 3c 25 c0 b8 00 00 <48> 8b 73 18 44 89 c7 44 89 45 98 ff 53 20 48 85 c0 48 89 c2 74 RIP [<ffffffff8111e28a>] mempool_alloc+0x4a/0x150 RSP <ffff880230699688> CR2: 0000000000000018 ---[ end trace 7a96042017ed21e2 ]--- Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2013-10-05Merge branch 'for-linus' into for-linus-3.12Chris Mason6-17/+31
2013-10-05Merge branch 'for-linus' of git://git.samba.org/sfrench/cifs-2.6Linus Torvalds10-115/+74
Pull CIFS fixes from Steve French: "Small set of cifs fixes. Most important is Jeff's fix that works around disconnection problems which can be caused by simultaneous use of user space tools (starting a long running smbclient backup then doing a cifs kernel mount) or multiple cifs mounts through a NAT, and Jim's fix to deal with reexport of cifs share. I expect to send two more cifs fixes next week (being tested now) - fixes to address an SMB2 unmount hang when server dies and a fix for cifs symlink handling of Windows "NFS" symlinks" * 'for-linus' of git://git.samba.org/sfrench/cifs-2.6: [CIFS] update cifs.ko version [CIFS] Remove ext2 flags that have been moved to fs.h [CIFS] Provide sane values for nlink cifs: stop trying to use virtual circuits CIFS: FS-Cache: Uncache unread pages in cifs_readpages() before freeing them
2013-10-05Merge tag 'pci-v3.12-fixes-1' of ↵Linus Torvalds1-1/+6
git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci Pull PCI fix from Bjorn Helgaas: "We merged what was intended to be an MMCONFIG cleanup, but in fact, for systems without _CBA (which is almost everything), it broke extended config space for domain 0 and it broke all config space for other domains. This reverts the change" * tag 'pci-v3.12-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: Revert "x86/PCI: MMCONFIG: Check earlier for MMCONFIG region at address zero"
2013-10-05Revert "x86/PCI: MMCONFIG: Check earlier for MMCONFIG region at address zero"Bjorn Helgaas1-1/+6
This reverts commit 07f9b61c3915e8eb156cb4461b3946736356ad02. 07f9b61c was intended to be a cleanup that didn't change anything, but in fact, for systems without _CBA (which is almost everything), it broke extended config space for domain 0 and all config space for other domains. Reference: http://lkml.kernel.org/r/20131004011806.GE20450@dangermouse.emea.sgi.com Reported-by: Hedi Berriche <hedi@sgi.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
2013-10-05Merge tag 'pm+acpi-3.12-rc4' of ↵Linus Torvalds6-5/+19
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull ACPI and power management fixes from Rafael Wysocki: - The resume part of user space driven hibernation (s2disk) is now broken after the change that moved the creation of memory bitmaps to after the freezing of tasks, because I forgot that the resume utility loaded the image before freezing tasks and needed the bitmaps for that. The fix adds special handling for that case. - One of recent commits changed the export of acpi_bus_get_device() to EXPORT_SYMBOL_GPL(), which was technically correct but broke existing binary modules using that function including one in particularly widespread use. Change it back to EXPORT_SYMBOL(). - The intel_pstate driver sometimes fails to disable turbo if its no_turbo sysfs attribute is set. Fix from Srinivas Pandruvada. - One of recent cpufreq fixes forgot to update a check in cpufreq-cpu0 which still (incorrectly) treats non-NULL as non-error. Fix from Philipp Zabel. - The SPEAr cpufreq driver uses a wrong variable type in one place preventing it from catching errors returned by one of the functions called by it. Fix from Sachin Kamat. * tag 'pm+acpi-3.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: ACPI: Use EXPORT_SYMBOL() for acpi_bus_get_device() intel_pstate: fix no_turbo cpufreq: cpufreq-cpu0: NULL is a valid regulator, part 2 cpufreq: SPEAr: Fix incorrect variable type PM / hibernate: Fix user space driven resume regression
2013-10-05Merge tag 'xfs-for-linus-v3.12-rc4' of git://oss.sgi.com/xfs/xfsLinus Torvalds6-42/+45
Pull xfs bugfixes from Ben Myers: "There are lockdep annotations for project quotas, a fix for dirent dtype support on v4 filesystems, a fix for a memory leak in recovery, and a fix for the build error that resulted from it. D'oh" * tag 'xfs-for-linus-v3.12-rc4' of git://oss.sgi.com/xfs/xfs: xfs: Use kmem_free() instead of free() xfs: fix memory leak in xlog_recover_add_to_trans xfs: dirent dtype presence is dependent on directory magic numbers xfs: lockdep needs to know about 3 dquot-deep nesting
2013-10-05selinux: remove 'flags' parameter from avc_audit()Linus Torvalds3-4/+4
Now avc_audit() has no more users with that parameter. Remove it. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-10-05selinux: avc_has_perm_flags has no more usersLinus Torvalds2-17/+6
.. so get rid of it. The only indirect users were all the avc_has_perm() callers which just expanded to have a zero flags argument. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-10-05Btrfs: fix a use-after-free bug in btrfs_dev_replace_finishingIlya Dryomov2-5/+7
free_device rcu callback, scheduled from btrfs_rm_dev_replace_srcdev, can be processed before btrfs_scratch_superblock is called, which would result in a use-after-free on btrfs_device contents. Fix this by zeroing the superblock before the rcu callback is registered. Cc: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
2013-10-05Btrfs: eliminate races in worker stopping codeIlya Dryomov2-6/+21
The current implementation of worker threads in Btrfs has races in worker stopping code, which cause all kinds of panics and lockups when running btrfs/011 xfstest in a loop. The problem is that btrfs_stop_workers is unsynchronized with respect to check_idle_worker, check_busy_worker and __btrfs_start_workers. E.g., check_idle_worker race flow: btrfs_stop_workers(): check_idle_worker(aworker): - grabs the lock - splices the idle list into the working list - removes the first worker from the working list - releases the lock to wait for its kthread's completion - grabs the lock - if aworker is on the working list, moves aworker from the working list to the idle list - releases the lock - grabs the lock - puts the worker - removes the second worker from the working list ...... btrfs_stop_workers returns, aworker is on the idle list FS is umounted, memory is freed ...... aworker is waken up, fireworks ensue With this applied, I wasn't able to trigger the problem in 48 hours, whereas previously I could reliably reproduce at least one of these races within an hour. Reported-by: David Sterba <dsterba@suse.cz> Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
2013-10-05Btrfs: fix crash of compressed writesLiu Bo1-1/+1
The crash[1] is found by xfstests/generic/208 with "-o compress", it's not reproduced everytime, but it does panic. The bug is quite interesting, it's actually introduced by a recent commit (573aecafca1cf7a974231b759197a1aebcf39c2a, Btrfs: actually limit the size of delalloc range). Btrfs implements delay allocation, so during writeback, we (1) get a page A and lock it (2) search the state tree for delalloc bytes and lock all pages within the range (3) process the delalloc range, including find disk space and create ordered extent and so on. (4) submit the page A. It runs well in normal cases, but if we're in a racy case, eg. buffered compressed writes and aio-dio writes, sometimes we may fail to lock all pages in the 'delalloc' range, in which case, we need to fall back to search the state tree again with a smaller range limit(max_bytes = PAGE_CACHE_SIZE - offset). The mentioned commit has a side effect, that is, in the fallback case, we can find delalloc bytes before the index of the page we already have locked, so we're in the case of (delalloc_end <= *start) and return with (found > 0). This ends with not locking delalloc pages but making ->writepage still process them, and the crash happens. This fixes it by just thinking that we find nothing and returning to caller as the caller knows how to deal with it properly. [1]: ------------[ cut here ]------------ kernel BUG at mm/page-writeback.c:2170! [...] CPU: 2 PID: 11755 Comm: btrfs-delalloc- Tainted: G O 3.11.0+ #8 [...] RIP: 0010:[<ffffffff810f5093>] [<ffffffff810f5093>] clear_page_dirty_for_io+0x1e/0x83 [...] [ 4934.248731] Stack: [ 4934.248731] ffff8801477e5dc8 ffffea00049b9f00 ffff8801869f9ce8 ffffffffa02b841a [ 4934.248731] 0000000000000000 0000000000000000 0000000000000fff 0000000000000620 [ 4934.248731] ffff88018db59c78 ffffea0005da8d40 ffffffffa02ff860 00000001810016c0 [ 4934.248731] Call Trace: [ 4934.248731] [<ffffffffa02b841a>] extent_range_clear_dirty_for_io+0xcf/0xf5 [btrfs] [ 4934.248731] [<ffffffffa02a8889>] compress_file_range+0x1dc/0x4cb [btrfs] [ 4934.248731] [<ffffffff8104f7af>] ? detach_if_pending+0x22/0x4b [ 4934.248731] [<ffffffffa02a8bad>] async_cow_start+0x35/0x53 [btrfs] [ 4934.248731] [<ffffffffa02c694b>] worker_loop+0x14b/0x48c [btrfs] [ 4934.248731] [<ffffffffa02c6800>] ? btrfs_queue_worker+0x25c/0x25c [btrfs] [ 4934.248731] [<ffffffff810608f5>] kthread+0x8d/0x95 [ 4934.248731] [<ffffffff81060868>] ? kthread_freezable_should_stop+0x43/0x43 [ 4934.248731] [<ffffffff814fe09c>] ret_from_fork+0x7c/0xb0 [ 4934.248731] [<ffffffff81060868>] ? kthread_freezable_should_stop+0x43/0x43 [ 4934.248731] Code: ff 85 c0 0f 94 c0 0f b6 c0 59 5b 5d c3 0f 1f 44 00 00 55 48 89 e5 41 54 53 48 89 fb e8 2c de 00 00 49 89 c4 48 8b 03 a8 01 75 02 <0f> 0b 4d 85 e4 74 52 49 8b 84 24 80 00 00 00 f6 40 20 01 75 44 [ 4934.248731] RIP [<ffffffff810f5093>] clear_page_dirty_for_io+0x1e/0x83 [ 4934.248731] RSP <ffff8801869f9c48> [ 4934.280307] ---[ end trace 36f06d3f8750236a ]--- Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com>