kernel/linux.git/drivers/block/zram, branch v5.10.258

zram: refuse to use zero sized block device as backing device

2025-01-09T12:24:54+00:00

commit be48c412f6ebf38849213c19547bc6d5b692b5e5 upstream. Patch series "zram: fix backing device setup issue", v2. This series fixes two bugs of backing device setting: - ZRAM should reject using a zero sized (or the uninitialized ZRAM device itself) as the backing device. - Fix backing device leaking when removing a uninitialized ZRAM device. This patch (of 2): Setting a zero sized block device as backing device is pointless, and one can easily create a recursive loop by setting the uninitialized ZRAM device itself as its own backing device by (zram0 is uninitialized): echo /dev/zram0 > /sys/block/zram0/backing_dev It's definitely a wrong config, and the module will pin itself, kernel should refuse doing so in the first place. By refusing to use zero sized device we avoided misuse cases including this one above. Link: https://lkml.kernel.org/r/20241209165717.94215-1-ryncsn@gmail.com Link: https://lkml.kernel.org/r/20241209165717.94215-2-ryncsn@gmail.com Fixes: 013bf95a83ec ("zram: add interface to specif backing device") Signed-off-by: Kairui Song Reported-by: Desheng Wu Reviewed-by: Sergey Senozhatsky Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

zram: do not lookup algorithm in backends table

2022-08-25T09:38:14+00:00

[ Upstream commit dc89997264de565999a1cb55db3f295d3a8e457b ] Always use crypto_has_comp() so that crypto can lookup module, call usermodhelper to load the modules, wait for usermodhelper to finish and so on. Otherwise crypto will do all of these steps under CPU hot-plug lock and this looks like too much stuff to handle under the CPU hot-plug lock. Besides this can end up in a deadlock when usermodhelper triggers a code path that attempts to lock the CPU hot-plug lock, that zram already holds. An example of such deadlock: - path A. zram grabs CPU hot-plug lock, execs /sbin/modprobe from crypto and waits for modprobe to finish disksize_store zcomp_create __cpuhp_state_add_instance __cpuhp_state_add_instance_cpuslocked zcomp_cpu_up_prepare crypto_alloc_base crypto_alg_mod_lookup call_usermodehelper_exec wait_for_completion_killable do_wait_for_common schedule - path B. async work kthread that brings in scsi device. It wants to register CPUHP states at some point, and it needs the CPU hot-plug lock for that, which is owned by zram. async_run_entry_fn scsi_probe_and_add_lun scsi_mq_alloc_queue blk_mq_init_queue blk_mq_init_allocated_queue blk_mq_realloc_hw_ctxs __cpuhp_state_add_instance __cpuhp_state_add_instance_cpuslocked mutex_lock schedule - path C. modprobe sleeps, waiting for all aync works to finish. load_module do_init_module async_synchronize_full async_synchronize_cookie_domain schedule [senozhatsky@chromium.org: add comment] Link: https://lkml.kernel.org/r/20220624060606.1014474-1-senozhatsky@chromium.org Link: https://lkml.kernel.org/r/20220622023501.517125-1-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky Cc: Minchan Kim Cc: Nitin Gupta Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

zram: off by one in read_block_state()

2021-11-18T13:04:27+00:00

[ Upstream commit a88e03cf3d190cf46bc4063a9b7efe87590de5f4 ] snprintf() returns the number of bytes it would have printed if there were space. But it does not count the NUL terminator. So that means that if "count == copied" then this has already overflowed by one character. This bug likely isn't super harmful in real life. Link: https://lkml.kernel.org/r/20210916130404.GA25094@kili Fixes: c0265342bff4 ("zram: introduce zram memory tracking") Signed-off-by: Dan Carpenter Cc: Minchan Kim Cc: Sergey Senozhatsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

zram: fix return value on writeback_store

2021-03-17T16:06:34+00:00

commit 57e0076e6575a7b7cef620a0bd2ee2549ef77818 upstream. writeback_store's return value is overwritten by submit_bio_wait's return value. Thus, writeback_store will return zero since there was no IO error. In the end, write syscall from userspace will see the zero as return value, which could make the process stall to keep trying the write until it will succeed. Link: https://lkml.kernel.org/r/20210312173949.2197662-1-minchan@kernel.org Fixes: 3b82a051c101("drivers/block/zram/zram_drv.c: fix error return codes not being returned in writeback_store") Signed-off-by: Minchan Kim Cc: Sergey Senozhatsky Cc: Colin Ian King Cc: John Dias Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

zsmalloc: account the number of compacted pages correctly

2021-03-07T11:34:15+00:00

commit 2395928158059b8f9858365fce7713ce7fef62e4 upstream. There exists multiple path may do zram compaction concurrently. 1. auto-compaction triggered during memory reclaim 2. userspace utils write zram/compaction node So, multiple threads may call zs_shrinker_scan/zs_compact concurrently. But pages_compacted is a per zsmalloc pool variable and modification of the variable is not serialized(through under class->lock). There are two issues here: 1. the pages_compacted may not equal to total number of pages freed(due to concurrently add). 2. zs_shrinker_scan may not return the correct number of pages freed(issued by current shrinker). The fix is simple: 1. account the number of pages freed in zs_compact locally. 2. use actomic variable pages_compacted to accumulate total number. Link: https://lkml.kernel.org/r/20210202122235.26885-1-wu-yan@tcl.com Fixes: 860c707dca155a56 ("zsmalloc: account the number of compacted pages") Signed-off-by: Rokudo Yan Cc: Minchan Kim Cc: Sergey Senozhatsky Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

Merge tag 'block-5.10-2020-10-24' of git://git.kernel.dk/linux-block

2020-10-24T19:46:42+00:00

Pull block fixes from Jens Axboe: - NVMe pull request from Christoph - rdma error handling fixes (Chao Leng) - fc error handling and reconnect fixes (James Smart) - fix the qid displace when tracing ioctl command (Keith Busch) - don't use BLK_MQ_REQ_NOWAIT for passthru (Chaitanya Kulkarni) - fix MTDT for passthru (Logan Gunthorpe) - blacklist Write Same on more devices (Kai-Heng Feng) - fix an uninitialized work struct (zhenwei pi)" - lightnvm out-of-bounds fix (Colin) - SG allocation leak fix (Doug) - rnbd fixes (Gioh, Guoqing, Jack) - zone error translation fixes (Keith) - kerneldoc markup fix (Mauro) - zram lockdep fix (Peter) - Kill unused io_context members (Yufen) - NUMA memory allocation cleanup (Xianting) - NBD config wakeup fix (Xiubo) * tag 'block-5.10-2020-10-24' of git://git.kernel.dk/linux-block: (27 commits) block: blk-mq: fix a kernel-doc markup nvme-fc: shorten reconnect delay if possible for FC nvme-fc: wait for queues to freeze before calling update_hr_hw_queues nvme-fc: fix error loop in create_hw_io_queues nvme-fc: fix io timeout to abort I/O null_blk: use zone status for max active/open nvmet: don't use BLK_MQ_REQ_NOWAIT for passthru nvmet: cleanup nvmet_passthru_map_sg() nvmet: limit passthru MTDS by BIO_MAX_PAGES nvmet: fix uninitialized work for zero kato nvme-pci: disable Write Zeroes on Sandisk Skyhawk nvme: use queuedata for nvme_req_qid nvme-rdma: fix crash due to incorrect cqe nvme-rdma: fix crash when connect rejected block: remove unused members for io_context blk-mq: remove the calling of local_memory_node() zram: Fix __zram_bvec_{read,write}() locking order skd_main: remove unused including sgl_alloc_order: fix memory leak lightnvm: fix out-of-bounds write to array devices->info[] ...

zram: Fix __zram_bvec_{read,write}() locking order

2020-10-19T15:32:28+00:00

Mikhail reported a lockdep spat detailing how __zram_bvec_read() and __zram_bvec_write() use zstrm->lock and zspage->lock in opposite order. Reported-by: Mikhail Gavrilov Signed-off-by: Peter Zijlstra (Intel) Tested-by: Mikhail Gavrilov Acked-by: Minchan Kim Acked-by: Sebastian Andrzej Siewior Signed-off-by: Jens Axboe

zram: failing to decompress is WARN_ON worthy

2020-10-16T18:11:18+00:00

If we fail to decompress in zram it's a pretty serious problem. We were entrusted to be able to decompress the old data but we failed. Either we've got some crazy bug in the compression code or we've got memory corruption. At the moment, when this happens the log looks like this: ERR kernel: [ 1833.099861] zram: Decompression failed! err=-22, page=336112 ERR kernel: [ 1833.099881] zram: Decompression failed! err=-22, page=336112 ALERT kernel: [ 1833.099886] Read-error on swap-device (253:0:2688896) It is true that we have an "ALERT" level log in there, but (at least to me) it feels like even this isn't enough to impart the seriousness of this error. Let's convert to a WARN_ON. Note that WARN_ON is automatically "unlikely" so we can simply replace the old annotation with the new one. Signed-off-by: Douglas Anderson Signed-off-by: Andrew Morton Acked-by: Minchan Kim Cc: Sergey Senozhatsky Cc: Sonny Rao Cc: Jens Axboe Link: https://lkml.kernel.org/r/20200917174059.1.If09c882545dbe432268f7a67a4d4cfcb6caace4f@changeid Signed-off-by: Linus Torvalds

bdi: replace BDI_CAP_STABLE_WRITES with a queue and a sb flag

2020-09-24T19:43:39+00:00

The BDI_CAP_STABLE_WRITES is one of the few bits of information in the backing_dev_info shared between the block drivers and the writeback code. To help untangling the dependency replace it with a queue flag and a superblock flag derived from it. This also helps with the case of e.g. a file system requiring stable writes due to its own checksumming, but not forcing it on other users of the block device like the swap code. One downside is that we an't support the stable_pages_required bdi attribute in sysfs anymore. It is replaced with a queue attribute which also is writable for easier testing. Signed-off-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Johannes Thumshirn Signed-off-by: Jens Axboe

bdi: remove BDI_CAP_SYNCHRONOUS_IO

2020-09-24T19:43:39+00:00

BDI_CAP_SYNCHRONOUS_IO is only checked in the swap code, and used to decided if ->rw_page can be used on a block device. Just check up for the method instead. The only complication is that zram needs a second set of block_device_operations as it can switch between modes that actually support ->rw_page and those who don't. Signed-off-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Johannes Thumshirn Signed-off-by: Jens Axboe