- 07 Sep, 2017 40 commits
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Michal Hocko authored
global_page_state is error prone as a recent bug report pointed out [1]. It only returns proper values for zone based counters as the enum it gets suggests. We already have global_node_page_state so let's rename global_page_state to global_zone_page_state to be more explicit here. All existing users seems to be correct: $ git grep "global_page_state(NR_" | sed 's@.*(\(NR_[A-Z_]*\)).*@\1@' | sort | uniq -c 2 NR_BOUNCE 2 NR_FREE_CMA_PAGES 11 NR_FREE_PAGES 1 NR_KERNEL_STACK_KB 1 NR_MLOCK 2 NR_PAGETABLE This patch shouldn't introduce any functional change. [1] http://lkml.kernel.org/r/201707260628.v6Q6SmaS030814@www262.sakura.ne.jp Link: http://lkml.kernel.org/r/20170801134256.5400-2-hannes@cmpxchg.orgSigned-off-by:Michal Hocko <mhocko@suse.com> Signed-off-by:
Johannes Weiner <hannes@cmpxchg.org> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Mike Kravetz authored
Use the common definitions from hugetlb_encode.h header file for encoding hugetlb size definitions in shmget system call flags. In addition, move these definitions from the internal (kernel) to user (uapi) header file. Link: http://lkml.kernel.org/r/1501527386-10736-4-git-send-email-mike.kravetz@oracle.comSigned-off-by:
Mike Kravetz <mike.kravetz@oracle.com> Suggested-by:
Matthew Wilcox <willy@infradead.org> Acked-by:
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Mike Kravetz authored
A non-default huge page size can be encoded in the flags argument of the mmap system call. The definitions for these encodings are in arch specific header files. However, all architectures use the same values. Consolidate all the definitions in the primary user header file (uapi/linux/mman.h). Include definitions for all known huge page sizes. Use the generic encoding definitions in hugetlb_encode.h as the basis for these definitions. Link: http://lkml.kernel.org/r/1501527386-10736-3-git-send-email-mike.kravetz@oracle.comSigned-off-by:
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Mike Kravetz authored
Patch series "Consolidate system call hugetlb page size encodings". These patches are the result of discussions in https://lkml.org/lkml/2017/3/8/548. The following changes are made in the patch set: 1) Put all the log2 encoded huge page size definitions in a common header file. The idea is have a set of definitions that can be use as the basis for system call specific definitions such as MAP_HUGE_* and SHM_HUGE_*. 2) Remove MAP_HUGE_* definitions in arch specific files. All these definitions are the same. Consolidate all definitions in the primary user header file (uapi/linux/mman.h). 3) Remove SHM_HUGE_* definitions intended for user space from kernel header file, and add to user (uapi/linux/shm.h) header file. Add definitions for all known huge page size encodings as in mmap. This patch (of 3): If hugetlb pages are requested in mmap or shmget system calls, a huge page size other than default can be requested. This is accomplished by encoding the log2 of the huge page size in the upper bits of the flag argument. asm-generic and arch specific headers all define the same values for these encodings. Put common definitions in a single header file. The primary uapi header files for mmap and shm will use these definitions as a basis for definitions specific to those system calls. Link: http://lkml.kernel.org/r/1501527386-10736-2-git-send-email-mike.kravetz@oracle.comSigned-off-by:
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Jeff Layton authored
Link: http://lkml.kernel.org/r/20170525102927.6163-1-jlayton@redhat.comSigned-off-by:
Jeff Layton <jlayton@redhat.com> Reviewed-by:
Jan Kara <jack@suse.cz> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by:
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Jeff Layton authored
fsync codepath assumes that f_mapping can never be NULL, but sync_file_range has a check for that. Remove the one from sync_file_range as I don't see how you'd ever get a NULL pointer in here. Link: http://lkml.kernel.org/r/20170525110509.9434-1-jlayton@redhat.comSigned-off-by:
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Mike Rapoport authored
Link: http://lkml.kernel.org/r/1497939652-16528-8-git-send-email-rppt@linux.vnet.ibm.comSigned-off-by:
Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Pavel Emelyanov <xemul@virtuozzo.com> Signed-off-by:
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Mike Rapoport authored
Now when shmem VMAs can be filled with zero page via userfaultfd we can report that UFFDIO_ZEROPAGE is available for those VMAs Link: http://lkml.kernel.org/r/1497939652-16528-7-git-send-email-rppt@linux.vnet.ibm.comSigned-off-by:
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Mike Rapoport authored
For shmem VMAs we can use shmem_mfill_zeropage_pte for UFFDIO_ZEROPAGE Link: http://lkml.kernel.org/r/1497939652-16528-6-git-send-email-rppt@linux.vnet.ibm.comSigned-off-by:
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Mike Rapoport authored
Shuffle the code a bit to improve readability. Link: http://lkml.kernel.org/r/1497939652-16528-5-git-send-email-rppt@linux.vnet.ibm.comSigned-off-by:
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Mike Rapoport authored
shmem_mfill_zeropage_pte is the low level routine that implements the userfaultfd UFFDIO_ZEROPAGE command. Since for shmem mappings zero pages are always allocated and accounted, the new method is a slight extension of the existing shmem_mcopy_atomic_pte. Link: http://lkml.kernel.org/r/1497939652-16528-4-git-send-email-rppt@linux.vnet.ibm.comSigned-off-by:
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Mike Rapoport authored
The shmem_acct_block and the update of used_blocks are following one another in all the places they are used. Combine these two into a helper function. Link: http://lkml.kernel.org/r/1497939652-16528-3-git-send-email-rppt@linux.vnet.ibm.comSigned-off-by:
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Mike Rapoport authored
Patch series "userfaultfd: enable zeropage support for shmem". These patches enable support for UFFDIO_ZEROPAGE for shared memory. The first two patches are not strictly related to userfaultfd, they are just minor refactoring to reduce amount of code duplication. This patch (of 7): Currently we update inode and shmem_inode_info before verifying that used_blocks will not exceed max_blocks. In case it will, we undo the update. Let's switch the order and move the verification of the blocks count before the inode and shmem_inode_info update. Link: http://lkml.kernel.org/r/1497939652-16528-2-git-send-email-rppt@linux.vnet.ibm.comSigned-off-by:
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Huang Ying authored
When swapping out THP (Transparent Huge Page), instead of swapping out the THP as a whole, sometimes we have to fallback to split the THP into normal pages before swapping, because no free swap clusters are available, or cgroup limit is exceeded, etc. To count the number of the fallback, a new VM event THP_SWPOUT_FALLBACK is added, and counted when we fallback to split the THP. Link: http://lkml.kernel.org/r/20170724051840.2309-13-ying.huang@intel.comSigned-off-by:
"Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c] Cc: Vishal L Verma <vishal.l.verma@intel.com> Signed-off-by:
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Huang Ying authored
In this patch, splitting transparent huge page (THP) during swapping out is delayed from after adding the THP into the swap cache to after swapping out finishes. After the patch, more operations for the anonymous THP reclaiming, such as writing the THP to the swap device, removing the THP from the swap cache could be batched. So that the performance of anonymous THP swapping out could be improved. This is the second step for the THP swap support. The plan is to delay splitting the THP step by step and avoid splitting the THP finally. With the patchset, the swap out throughput improves 42% (from about 5.81GB/s to about 8.25GB/s) in the vm-scalability swap-w-seq test case with 16 processes. At the same time, the IPI (reflect TLB flushing) reduced about 78.9%. The test is done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. To test the sequential swapping out, the test case creates 8 processes, which sequentially allocate and write to the anonymous pages until the RAM and part of the swap device is used up. Link: http://lkml.kernel.org/r/20170724051840.2309-12-ying.huang@intel.comSigned-off-by:
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Huang Ying authored
This patch makes mem_cgroup_swapout() works for the transparent huge page (THP). Which will move the memory cgroup charge from memory to swap for a THP. This will be used for the THP swap support. Where a THP may be swapped out as a whole to a set of (HPAGE_PMD_NR) continuous swap slots on the swap device. Link: http://lkml.kernel.org/r/20170724051840.2309-11-ying.huang@intel.comSigned-off-by:
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Huang Ying authored
For a THP (Transparent Huge Page), tail_page->mem_cgroup is NULL. So to check whether the page is charged already, we need to check the head page. This is not an issue before because it is impossible for a THP to be in the swap cache before. But after we add delaying splitting THP after swapped out support, it is possible now. Link: http://lkml.kernel.org/r/20170724051840.2309-10-ying.huang@intel.comSigned-off-by:
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Huang Ying authored
PTE mapped THP (Transparent Huge Page) will be ignored when moving memory cgroup charge. But for THP which is in the swap cache, the memory cgroup charge for the swap of a tail-page may be moved in current implementation. That isn't correct, because the swap charge for all sub-pages of a THP should be moved together. Following the processing of the PTE mapped THP, the mem cgroup charge moving for the swap entry for a tail-page of a THP is ignored too. Link: http://lkml.kernel.org/r/20170724051840.2309-9-ying.huang@intel.comSigned-off-by:
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Huang Ying authored
After adding swapping out support for THP (Transparent Huge Page), it is possible that a THP in swap cache (partly swapped out) need to be split. To split such a THP, the swap cluster backing the THP need to be split too, that is, the CLUSTER_FLAG_HUGE flag need to be cleared for the swap cluster. The patch implemented this. And because the THP swap writing needs the THP keeps as huge page during writing. The PageWriteback flag is checked before splitting. Link: http://lkml.kernel.org/r/20170724051840.2309-8-ying.huang@intel.comSigned-off-by:
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Huang Ying authored
To support delay splitting THP (Transparent Huge Page) after swapped out, we need to enhance swap writing code to support to write a THP as a whole. This will improve swap write IO performance. As Ming Lei <ming.lei@redhat.com> pointed out, this should be based on multipage bvec support, which hasn't been merged yet. So this patch is only for testing the functionality of the other patches in the series. And will be reimplemented after multipage bvec support is merged. Link: http://lkml.kernel.org/r/20170724051840.2309-7-ying.huang@intel.comSigned-off-by:
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Huang Ying authored
The .rw_page in struct block_device_operations is used by the swap subsystem to read/write the page contents from/into the corresponding swap slot in the swap device. To support the THP (Transparent Huge Page) swap optimization, the .rw_page is enhanced to support to read/write THP if possible. Link: http://lkml.kernel.org/r/20170724051840.2309-6-ying.huang@intel.comSigned-off-by:
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Huang Ying authored
It's hard to write a whole transparent huge page (THP) to a file backed swap device during swapping out and the file backed swap device isn't very popular. So the huge cluster allocation for the file backed swap device is disabled. Link: http://lkml.kernel.org/r/20170724051840.2309-5-ying.huang@intel.comSigned-off-by:
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Huang Ying authored
After supporting to delay THP (Transparent Huge Page) splitting after swapped out, it is possible that some page table mappings of the THP are turned into swap entries. So reuse_swap_page() need to check the swap count in addition to the map count as before. This patch done that. In the huge PMD write protect fault handler, in addition to the page map count, the swap count need to be checked too, so the page lock need to be acquired too when calling reuse_swap_page() in addition to the page table lock. [ying.huang@intel.com: silence a compiler warning] Link: http://lkml.kernel.org/r/87bmnzizjy.fsf@yhuang-dev.intel.com Link: http://lkml.kernel.org/r/20170724051840.2309-4-ying.huang@intel.comSigned-off-by:
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Huang Ying authored
The normal swap slot reclaiming can be done when the swap count reaches SWAP_HAS_CACHE. But for the swap slot which is backing a THP, all swap slots backing one THP must be reclaimed together, because the swap slot may be used again when the THP is swapped out again later. So the swap slots backing one THP can be reclaimed together when the swap count for all swap slots for the THP reached SWAP_HAS_CACHE. In the patch, the functions to check whether the swap count for all swap slots backing one THP reached SWAP_HAS_CACHE are implemented and used when checking whether a swap slot can be reclaimed. To make it easier to determine whether a swap slot is backing a THP, a new swap cluster flag named CLUSTER_FLAG_HUGE is added to mark a swap cluster which is backing a THP (Transparent Huge Page). Because THP swap in as a whole isn't supported now. After deleting the THP from the swap cache (for example, swapping out finished), the CLUSTER_FLAG_HUGE flag will be cleared. So that, the normal pages inside THP can be swapped in individually. [ying.huang@intel.com: fix swap_page_trans_huge_swapped on HDD] Link: http://lkml.kernel.org/r/874ltsm0bi.fsf@yhuang-dev.intel.com Link: http://lkml.kernel.org/r/20170724051840.2309-3-ying.huang@intel.comSigned-off-by:
Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Michal Hocko <mhocko@kernel.org> Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c] Cc: Vishal L Verma <vishal.l.verma@intel.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by:
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Huang Ying authored
Patch series "mm, THP, swap: Delay splitting THP after swapped out", v3. This is the second step of THP (Transparent Huge Page) swap optimization. In the first step, the splitting huge page is delayed from almost the first step of swapping out to after allocating the swap space for the THP and adding the THP into the swap cache. In the second step, the splitting is delayed further to after the swapping out finished. The plan is to delay splitting THP step by step, finally avoid splitting THP for the THP swapping out and swap out/in the THP as a whole. In the patchset, more operations for the anonymous THP reclaiming, such as TLB flushing, writing the THP to the swap device, removing the THP from the swap cache are batched. So that the performance of anonymous THP swapping out are improved. During the development, the following scenarios/code paths have been checked, - swap out/in - swap off - write protect page fault - madvise_free - process exit - split huge page With the patchset, the swap out throughput improves 42% (from about 5.81GB/s to about 8.25GB/s) in the vm-scalability swap-w-seq test case with 16 processes. At the same time, the IPI (reflect TLB flushing) reduced about 78.9%. The test is done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. To test the sequential swapping out, the test case creates 8 processes, which sequentially allocate and write to the anonymous pages until the RAM and part of the swap device is used up. Below is the part of the cover letter for the first step patchset of THP swap optimization which applies to all steps. ========================= Recently, the performance of the storage devices improved so fast that we cannot saturate the disk bandwidth with single logical CPU when do page swap out even on a high-end server machine. Because the performance of the storage device improved faster than that of single logical CPU. And it seems that the trend will not change in the near future. On the other hand, the THP becomes more and more popular because of increased memory size. So it becomes necessary to optimize THP swap performance. The advantages of the THP swap support include: - Batch the swap operations for the THP to reduce TLB flushing and lock acquiring/releasing, including allocating/freeing the swap space, adding/deleting to/from the swap cache, and writing/reading the swap space, etc. This will help improve the performance of the THP swap. - The THP swap space read/write will be 2M sequential IO. It is particularly helpful for the swap read, which are usually 4k random IO. This will improve the performance of the THP swap too. - It will help the memory fragmentation, especially when the THP is heavily used by the applications. The 2M continuous pages will be free up after THP swapping out. - It will improve the THP utilization on the system with the swap turned on. Because the speed for khugepaged to collapse the normal pages into the THP is quite slow. After the THP is split during the swapping out, it will take quite long time for the normal pages to collapse back into the THP after being swapped in. The high THP utilization helps the efficiency of the page based memory management too. There are some concerns regarding THP swap in, mainly because possible enlarged read/write IO size (for swap in/out) may put more overhead on the storage device. To deal with that, the THP swap in should be turned on only when necessary. For example, it can be selected via "always/never/madvise" logic, to be turned on globally, turned off globally, or turned on only for VMA with MADV_HUGEPAGE, etc. This patch (of 12): Previously, swapcache_free_cluster() is used only in the error path of shrink_page_list() to free the swap cluster just allocated if the THP (Transparent Huge Page) is failed to be split. In this patch, it is enhanced to clear the swap cache flag (SWAP_HAS_CACHE) for the swap cluster that holds the contents of THP swapped out. This will be used in delaying splitting THP after swapping out support. Because there is no THP swapping in as a whole support yet, after clearing the swap cache flag, the swap cluster backing the THP swapped out will be split. So that the swap slots in the swap cluster can be swapped in as normal pages later. Link: http://lkml.kernel.org/r/20170724051840.2309-2-ying.huang@intel.comSigned-off-by:
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Matthias Kaehlcke authored
Several functions use an enum type as parameter for an event/state, but are called in some locations with an argument of a different enum type. Adjust the interface of these functions to reality by changing the parameter to int. This fixes a ton of enum-conversion warnings that are generated when building the kernel with clang. [mka@chromium.org: also change parameter type of inc/dec/mod_memcg_page_state()] Link: http://lkml.kernel.org/r/20170728213442.93823-1-mka@chromium.org Link: http://lkml.kernel.org/r/20170727211004.34435-1-mka@chromium.orgSigned-off-by:
Matthias Kaehlcke <mka@chromium.org> Acked-by:
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Arvind Yadav authored
attribute_group are not supposed to change at runtime. All functions working with attribute_group provided by <linux/sysfs.h> work with const attribute_group. So mark the non-const structs as const. Link: http://lkml.kernel.org/r/1501157260-3922-1-git-send-email-arvind.yadav.cs@gmail.comSigned-off-by:
Arvind Yadav <arvind.yadav.cs@gmail.com> Signed-off-by:
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Arvind Yadav authored
attribute_group are not supposed to change at runtime. All functions working with attribute_group provided by <linux/sysfs.h> work with const attribute_group. So mark the non-const structs as const. Link: http://lkml.kernel.org/r/1501157240-3876-1-git-send-email-arvind.yadav.cs@gmail.comSigned-off-by:
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Arvind Yadav authored
attribute_group are not supposed to change at runtime. All functions working with attribute_group provided by <linux/sysfs.h> work with const attribute_group. So mark the non-const structs as const. Link: http://lkml.kernel.org/r/1501157221-3832-1-git-send-email-arvind.yadav.cs@gmail.comSigned-off-by:
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Arvind Yadav authored
attribute_group are not supposed to change at runtime. All functions working with attribute_group provided by <linux/sysfs.h> work with const attribute_group. So mark the non-const structs as const. Link: http://lkml.kernel.org/r/1501157186-3749-1-git-send-email-arvind.yadav.cs@gmail.comSigned-off-by:
Christoph Lameter <cl@linux.com> Signed-off-by:
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Arvind Yadav authored
attribute_group are not supposed to change at runtime. All functions working with attribute_group provided by <linux/sysfs.h> work with const attribute_group. So mark the non-const structs as const. Link: http://lkml.kernel.org/r/1501157167-3706-2-git-send-email-arvind.yadav.cs@gmail.comSigned-off-by:
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Roman Gushchin authored
Commit fa06235b ("cgroup: reset css on destruction") caused css_reset callback to be called from the offlining path. Although it solves the problem mentioned in the commit description ("For instance, memory cgroup needs to reset memory.low, otherwise pages charged to a dead cgroup might never get reclaimed."), generally speaking, it's not correct. An offline cgroup can still be a resource domain, and we shouldn't grant it more resources than it had before deletion. For instance, if an offline memory cgroup has dirty pages, we should still imply i/o limits during writeback. The css_reset callback is designed to return the cgroup state into the original state, that means reset all limits and counters. It's spomething different from the offlining, and we shouldn't use it from the offlining path. Instead, we should adjust necessary settings from the per-controller css_offline callbacks (e.g. reset memory.low). Link: http://lkml.kernel.org/r/20170727130428.28856-2-guro@fb.comSigned-off-by:
Roman Gushchin <guro@fb.com> Acked-by:
Tejun Heo <tj@kernel.org> Acked-by:
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Roman Gushchin authored
A removed memory cgroup with a defined memory.low and some belonging pagecache has very low chances to be freed. If a cgroup has been removed, there is likely no memory pressure inside the cgroup, and the pagecache is protected from the external pressure by the defined low limit. The cgroup will be freed only after the reclaim of all belonging pages. And it will not happen until there are any reclaimable memory in the system. That means, there is a good chance, that a cold pagecache will reside in the memory for an undefined amount of time, wasting system resources. This problem was fixed earlier by fa06235b ("cgroup: reset css on destruction"), but it's not a best way to do it, as we can't really reset all limits/counters during cgroup offlining. Link: http://lkml.kernel.org/r/20170727130428.28856-1-guro@fb.comSigned-off-by:
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Jan Kara authored
All users of pagevec_lookup() and pagevec_lookup_range() now pass PAGEVEC_SIZE as a desired number of pages. Just drop the argument. Link: http://lkml.kernel.org/r/20170726114704.7626-11-jack@suse.czSigned-off-by:
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Jan Kara authored
We want only pages from given range in filemap_range_has_page(), furthermore we want at most a single page. So use find_get_pages_range() instead of pagevec_lookup() and remove unnecessary code. Link: http://lkml.kernel.org/r/20170726114704.7626-10-jack@suse.czSigned-off-by:
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Jan Kara authored
We want only pages from given range in page_cache_seek_hole_data(). Use pagevec_lookup_range() instead of pagevec_lookup() and remove unnecessary code. Note that the check for getting less pages than desired can be removed because index gets updated by pagevec_lookup_range(). Link: http://lkml.kernel.org/r/20170726114704.7626-9-jack@suse.czSigned-off-by:
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Jan Kara authored
We want only pages from given range in remove_inode_hugepages(). Use pagevec_lookup_range() instead of pagevec_lookup(). Link: http://lkml.kernel.org/r/20170726114704.7626-8-jack@suse.czSigned-off-by:
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Jan Kara authored
Both occurences of pagevec_lookup() actually want only pages from a given range. Use pagevec_lookup_range() for the lookup. Link: http://lkml.kernel.org/r/20170726114704.7626-7-jack@suse.czSigned-off-by:
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Jan Kara authored
Use pagevec_lookup_range() in ext4_find_unwritten_pgoff() since we are interested only in pages in the given range. Simplify the logic as a result of not getting pages out of range and index getting automatically advanced. Link: http://lkml.kernel.org/r/20170726114704.7626-6-jack@suse.czSigned-off-by:
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Jan Kara authored
Commit e64855c6 ("fs: Add helper to clean bdev aliases under a bh and use it") added a wrapper for clean_bdev_aliases() that invalidates bdev aliases underlying a single buffer head. However this has caused a performance regression for bonnie++ benchmark on ext4 filesystem when delayed allocation is turned off (ext3 mode) - average of 3 runs: Hmean SeqOut Char 164787.55 ( 0.00%) 107189.06 (-34.95%) Hmean SeqOut Block 219883.89 ( 0.00%) 168870.32 (-23.20%) The reason for this regression is that clean_bdev_aliases() is slower when called for a single block because pagevec_lookup() it uses will end up iterating through the radix tree until it finds a page (which may take a while) but we are only interested whether there's a page at a particular index. Fix the problem by using pagevec_lookup_range() instead which avoids the needless iteration. Fixes: e64855c6 ("fs: Add helper to clean bdev aliases under a bh and use it") Link: http://lkml.kernel.org/r/20170726114704.7626-5-jack@suse.czSigned-off-by:
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