kernel/linux.git/drivers/block/zram, branch v4.11.5

zram: do not use copy_page with non-page aligned address

2017-04-14T01:24:21+00:00

The copy_page is optimized memcpy for page-alinged address. If it is used with non-page aligned address, it can corrupt memory which means system corruption. With zram, it can happen with 1. 64K architecture 2. partial IO 3. slub debug Partial IO need to allocate a page and zram allocates it via kmalloc. With slub debug, kmalloc(PAGE_SIZE) doesn't return page-size aligned address. And finally, copy_page(mem, cmem) corrupts memory. So, this patch changes it to memcpy. Actuaully, we don't need to change zram_bvec_write part because zsmalloc returns page-aligned address in case of PAGE_SIZE class but it's not good to rely on the internal of zsmalloc. Note: When this patch is merged to stable, clear_page should be fixed, too. Unfortunately, recent zram removes it by "same page merge" feature so it's hard to backport this patch to -stable tree. I will handle it when I receive the mail from stable tree maintainer to merge this patch to backport. Fixes: 42e99bd ("zram: optimize memory operations with clear_page()/copy_page()") Link: http://lkml.kernel.org/r/1492042622-12074-2-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim Cc: Sergey Senozhatsky Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: fix operator precedence to get offset

2017-04-14T01:24:21+00:00

In zram_rw_page, the logic to get offset is wrong by operator precedence (i.e., "<<" is higher than "&"). With wrong offset, zram can corrupt the user's data. This patch fixes it. Fixes: 8c7f01025 ("zram: implement rw_page operation of zram") Link: http://lkml.kernel.org/r/1492042622-12074-1-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim Cc: Sergey Senozhatsky Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: set physical queue limits to avoid array out of bounds accesses

2017-03-08T16:56:12+00:00

zram can handle at most SECTORS_PER_PAGE sectors in a bio's bvec. When using the NVMe over Fabrics loopback target which potentially sends a huge bulk of pages attached to the bio's bvec this results in a kernel panic because of array out of bounds accesses in zram_decompress_page(). Signed-off-by: Johannes Thumshirn Reviewed-by: Hannes Reinecke Reviewed-by: Sergey Senozhatsky Signed-off-by: Jens Axboe

zram: extend zero pages to same element pages

2017-02-25T01:46:56+00:00

The idea is that without doing more calculations we extend zero pages to same element pages for zram. zero page is special case of same element page with zero element. 1. the test is done under android 7.0 2. startup too many applications circularly 3. sample the zero pages, same pages (none-zero element) and total pages in function page_zero_filled the result is listed as below: ZERO SAME TOTAL 36214 17842 598196 ZERO/TOTAL SAME/TOTAL (ZERO+SAME)/TOTAL ZERO/SAME AVERAGE 0.060631909 0.024990816 0.085622726 2.663825038 STDEV 0.00674612 0.005887625 0.009707034 2.115881328 MAX 0.069698422 0.030046087 0.094975336 7.56043956 MIN 0.03959586 0.007332205 0.056055193 1.928985507 from the above data, the benefit is about 2.5% and up to 3% of total swapout pages. The defect of the patch is that when we recovery a page from non-zero element the operations are low efficient for partial read. This patch extends zero_page to same_page so if there is any user to have monitored zero_pages, he will be surprised if the number is increased but it's not harmful, I believe. [minchan@kernel.org: do not free same element pages in zram_meta_free] Link: http://lkml.kernel.org/r/20170207065741.GA2567@bbox Link: http://lkml.kernel.org/r/1483692145-75357-1-git-send-email-zhouxianrong@huawei.com Link: http://lkml.kernel.org/r/1486307804-27903-1-git-send-email-minchan@kernel.org Signed-off-by: zhouxianrong Signed-off-by: Minchan Kim Cc: Sergey Senozhatsky Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: remove waitqueue for IO done

2017-02-25T01:46:54+00:00

zram_reset_device() waits for ongoing writepage pages to be completed by zram->refcount logic. However, it's pointless because before the reset, we prevent further opening of zram by zram->claim and flush all of pending IO by fsync_bdev so there should be no pending IO at the zram_reset_device(). So let's remove that code which is even broken due to the lack of wake_up elsewhere. Link: http://lkml.kernel.org/r/1485145031-11661-1-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim Reviewed-by: Sergey Senozhatsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: remove obsolete sysfs attrs

2017-02-23T00:41:30+00:00

We had a deprecated_attr_warn() warning for 2 years and now the time has come and we finally can do the cleanup. The plan was as follows: : per-stat sysfs attributes are considered to be deprecated. : The basic strategy is: : -- the existing RW nodes will be downgraded to WO nodes (in linux 4.11) : -- deprecated RO sysfs nodes will eventually be removed (in linux 4.11) : : The list of deprecated attributes can be found here: : Documentation/ABI/obsolete/sysfs-block-zram : : Basically, every attribute that has its own read accessible sysfs : node (e.g. num_reads) *AND* is accessible via one of the stat files : (zram/stat or zram/io_stat or zram/mm_stat) is considered : to be deprecated. The patch also removes `obsolete/sysfs-block-zram', clean ups `testing/sysfs-block-zram' and tweaks zram.txt files. Link: http://lkml.kernel.org/r/20170118035838.11090-1-sergey.senozhatsky@gmail.com Signed-off-by: Sergey Senozhatsky Acked-by: Minchan Kim Cc: Jonathan Corbet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram_drv: update for backing dev info changes

2017-02-02T23:53:07+00:00

A previous commit made the bdi embedded in the request queue a pointer, but neglected to fixup zram. Fix it up. Fixes: dc3b17cc8bf ("block: Use pointer to backing_dev_info from request_queue") Reported-by: Bart Van Assche Signed-off-by: Jens Axboe

zram: support BDI_CAP_STABLE_WRITES

2017-01-11T02:31:55+00:00

zram has used per-cpu stream feature from v4.7. It aims for increasing cache hit ratio of scratch buffer for compressing. Downside of that approach is that zram should ask memory space for compressed page in per-cpu context which requires stricted gfp flag which could be failed. If so, it retries to allocate memory space out of per-cpu context so it could get memory this time and compress the data again, copies it to the memory space. In this scenario, zram assumes the data should never be changed but it is not true without stable page support. So, If the data is changed under us, zram can make buffer overrun so that zsmalloc free object chain is broken so system goes crash like below https://bugzilla.suse.com/show_bug.cgi?id=997574 This patch adds BDI_CAP_STABLE_WRITES to zram for declaring "I am block device needing *stable write*". Fixes: da9556a2367c ("zram: user per-cpu compression streams") Link: http://lkml.kernel.org/r/1482366980-3782-4-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim Reviewed-by: Sergey Senozhatsky Cc: Takashi Iwai Cc: Hyeoncheol Lee Cc: Cc: Sangseok Lee Cc: Hugh Dickins Cc: Darrick J. Wong Cc: [4.7+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: revalidate disk under init_lock

2017-01-11T02:31:55+00:00

Commit b4c5c60920e3 ("zram: avoid lockdep splat by revalidate_disk") moved revalidate_disk call out of init_lock to avoid lockdep false-positive splat. However, commit 08eee69fcf6b ("zram: remove init_lock in zram_make_request") removed init_lock in IO path so there is no worry about lockdep splat. So, let's restore it. This patch is needed to set BDI_CAP_STABLE_WRITES atomically in next patch. Fixes: da9556a2367c ("zram: user per-cpu compression streams") Link: http://lkml.kernel.org/r/1482366980-3782-3-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim Reviewed-by: Sergey Senozhatsky Cc: Takashi Iwai Cc: Hyeoncheol Lee Cc: Cc: Sangseok Lee Cc: Hugh Dickins Cc: Darrick J. Wong Cc: [4.7+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-12-13T03:25:04+00:00

Pull smp hotplug updates from Thomas Gleixner: "This is the final round of converting the notifier mess to the state machine. The removal of the notifiers and the related infrastructure will happen around rc1, as there are conversions outstanding in other trees. The whole exercise removed about 2000 lines of code in total and in course of the conversion several dozen bugs got fixed. The new mechanism allows to test almost every hotplug step standalone, so usage sites can exercise all transitions extensively. There is more room for improvement, like integrating all the pointlessly different architecture mechanisms of synchronizing, setting cpus online etc into the core code" * 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) tracing/rb: Init the CPU mask on allocation soc/fsl/qbman: Convert to hotplug state machine soc/fsl/qbman: Convert to hotplug state machine zram: Convert to hotplug state machine KVM/PPC/Book3S HV: Convert to hotplug state machine arm64/cpuinfo: Convert to hotplug state machine arm64/cpuinfo: Make hotplug notifier symmetric mm/compaction: Convert to hotplug state machine iommu/vt-d: Convert to hotplug state machine mm/zswap: Convert pool to hotplug state machine mm/zswap: Convert dst-mem to hotplug state machine mm/zsmalloc: Convert to hotplug state machine mm/vmstat: Convert to hotplug state machine mm/vmstat: Avoid on each online CPU loops mm/vmstat: Drop get_online_cpus() from init_cpu_node_state/vmstat_cpu_dead() tracing/rb: Convert to hotplug state machine oprofile/nmi timer: Convert to hotplug state machine net/iucv: Use explicit clean up labels in iucv_init() x86/pci/amd-bus: Convert to hotplug state machine x86/oprofile/nmi: Convert to hotplug state machine ...