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2019-09-11swiotlb-xen: use the same foreign page check everywhereChristoph Hellwig1-22/+9
xen_dma_map_page uses a different and more complicated check for foreign pages than the other three cache maintainance helpers. Switch it to the simpler pfn_valid method a well, and document the scheme with a single improved comment in xen_dma_map_page. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
2019-09-11swiotlb-xen: remove xen_swiotlb_dma_mmap and xen_swiotlb_dma_get_sgtableChristoph Hellwig1-27/+2
There is no need to wrap the common version, just wire them up directly. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
2019-09-11xen: remove the exports for xen_{create,destroy}_contiguous_regionChristoph Hellwig2-4/+0
These routines are only used by swiotlb-xen, which cannot be modular. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
2019-09-11xen/arm: remove xen_dma_opsChristoph Hellwig4-8/+4
arm and arm64 can just use xen_swiotlb_dma_ops directly like x86, no need for a pointer indirection. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Julien Grall <julien.grall@arm.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
2019-09-11xen/arm: simplify dma_cache_maintChristoph Hellwig1-40/+21
Calculate the required operation in the caller, and pass it directly instead of recalculating it for each page, and use simple arithmetics to get from the physical address to Xen page size aligned chunks. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
2019-09-11xen/arm: use dev_is_dma_coherentChristoph Hellwig3-21/+6
Use the dma-noncoherent dev_is_dma_coherent helper instead of the home grown variant. Note that both are always initialized to the same value in arch_setup_dma_ops. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Julien Grall <julien.grall@arm.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
2019-09-11xen/arm: consolidate page-coherent.hChristoph Hellwig3-150/+80
Shared the duplicate arm/arm64 code in include/xen/arm/page-coherent.h. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
2019-09-11xen/arm: use dma-noncoherent.h calls for xen-swiotlb cache maintainanceChristoph Hellwig4-75/+28
Copy the arm64 code that uses the dma-direct/swiotlb helpers for DMA on-coherent devices. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
2019-09-04arm: remove wrappers for the generic dma remap helpersChristoph Hellwig1-27/+5
Remove a few tiny wrappers around the generic dma remap code. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: introduce a dma_common_find_pages helperChristoph Hellwig4-20/+16
A helper to find the backing page array based on a virtual address. This also ensures we do the same vm_flags check everywhere instead of slightly different or missing ones in a few places. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: always use VM_DMA_COHERENT for generic DMA remapChristoph Hellwig5-28/+21
Currently the generic dma remap allocator gets a vm_flags passed by the caller that is a little confusing. We just introduced a generic vmalloc-level flag to identify the dma coherent allocations, so use that everywhere and remove the now pointless argument. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04vmalloc: lift the arm flag for coherent mappings to common codeChristoph Hellwig4-19/+13
The arm architecture had a VM_ARM_DMA_CONSISTENT flag to mark DMA coherent remapping for a while. Lift this flag to common code so that we can use it generically. We also check it in the only place VM_USERMAP is directly check so that we can entirely replace that flag as well (although I'm not even sure why we'd want to allow remapping DMA appings, but I'd rather not change behavior). Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: provide a better default ->get_required_maskChristoph Hellwig4-27/+14
Most dma_map_ops instances are IOMMUs that work perfectly fine in 32-bits of IOVA space, and the generic direct mapping code already provides its own routines that is intelligent based on the amount of memory actually present. Wire up the dma-direct routine for the ARM direct mapping code as well, and otherwise default to the constant 32-bit mask. This way we only need to override it for the occasional odd IOMMU that requires 64-bit IOVA support, or IOMMU drivers that are more efficient if they can fall back to the direct mapping. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: remove the dma_declare_coherent_memory exportChristoph Hellwig1-1/+0
dma_declare_coherent_memory is something that the platform setup code (which pretty much means the device tree these days) need to do so that drivers can use the memory as declared by the platform. Drivers themselves have no business calling this function. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04remoteproc: don't allow modular buildChristoph Hellwig1-1/+1
Remoteproc started using dma_declare_coherent_memory recently, which is a bad idea from drivers, and the maintainers agreed to fix that. But until that is fixed only allow building the driver built in so that we can remove the dma_declare_coherent_memory export and prevent other drivers from "accidentally" using it like remoteproc. Note that the driver would also leak the declared coherent memory on unload if it actually was built as a module at the moment. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2019-09-04dma-mapping: remove the dma_mmap_from_dev_coherent exportChristoph Hellwig1-1/+0
dma_mmap_from_dev_coherent is only used by dma_map_ops instances, none of which is modular. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: remove dma_release_declared_memoryChristoph Hellwig3-28/+0
This function is entirely unused given that declared memory is generally provided by platform setup code. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: remove dma_{alloc,free,mmap}_writecombineChristoph Hellwig2-15/+5
We can already use DMA_ATTR_WRITE_COMBINE or the _wc prefixed version, so remove the third way of doing things. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
2019-09-04dma-mapping: remove CONFIG_ARCH_NO_COHERENT_DMA_MMAPChristoph Hellwig7-15/+5
CONFIG_ARCH_NO_COHERENT_DMA_MMAP is now functionally identical to !CONFIG_MMU, so remove the separate symbol. The only difference is that arm did not set it for !CONFIG_MMU, but arm uses a separate dma mapping implementation including its own mmap method, which is handled by moving the CONFIG_MMU check in dma_can_mmap so that is only applies to the dma-direct case, just as the other ifdefs for it. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
2019-09-04parisc: don't set ARCH_NO_COHERENT_DMA_MMAPChristoph Hellwig3-3/+0
parisc is the only architecture that sets ARCH_NO_COHERENT_DMA_MMAP when an MMU is enabled. AFAIK this is because parisc CPUs use VIVT caches, which means exporting normally cachable memory to userspace is relatively dangrous due to cache aliasing. But normally cachable memory is only allocated by dma_alloc_coherent on parisc when using the sba_iommu or ccio_iommu drivers, so just remove the .mmap implementation for them so that we don't have to set ARCH_NO_COHERENT_DMA_MMAP, which I plan to get rid of. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04arm-nommu: call dma_mmap_from_dev_coherent directlyChristoph Hellwig1-2/+3
There is no need to go through dma_common_mmap for the arm-nommu dma mmap implementation as the only possible memory not handled above could be that from the per-device coherent pool. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04ALSA: pcm: use dma_can_mmap() to check if a device supports dma_mmap_*Christoph Hellwig1-7/+6
Replace the local hack with the dma_can_mmap helper to check if a given device supports mapping DMA allocations to userspace. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Takashi Iwai <tiwai@suse.de>
2019-09-04dma-mapping: add a dma_can_mmap helperChristoph Hellwig2-0/+28
Add a helper to check if DMA allocations for a specific device can be mapped to userspace using dma_mmap_*. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: explicitly wire up ->mmap and ->get_sgtableChristoph Hellwig15-8/+42
While the default ->mmap and ->get_sgtable implementations work for the majority of our dma_map_ops impementations they are inherently safe for others that don't use the page allocator or CMA and/or use their own way of remapping not covered by the common code. So remove the defaults if these methods are not wired up, but instead wire up the default implementations for all safe instances. Fixes: e1c7e324539a ("dma-mapping: always provide the dma_map_ops based implementation") Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: move the dma_get_sgtable API comments from arm to common codeChristoph Hellwig2-11/+11
The comments are spot on and should be near the central API, not just near a single implementation. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-03dma-mapping: fix filename referencesAndy Shevchenko5-7/+4
After commit cf65a0f6f6ff ("dma-mapping: move all DMA mapping code to kernel/dma") some of the files are referring to outdated information, i.e. old file names of DMA mapping sources. Fix it here. Note, the lines with "Glue code for..." have been removed completely. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-03iommu/dma: add a new dma_map_ops of get_merge_boundary()Yoshihiro Shimoda1-0/+8
This patch adds a new dma_map_ops of get_merge_boundary() to expose the DMA merge boundary if the domain type is IOMMU_DOMAIN_DMA. Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Reviewed-by: Simon Horman <horms+renesas@verge.net.au> Acked-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-03dma-mapping: introduce dma_get_merge_boundary()Yoshihiro Shimoda3-0/+25
This patch adds a new DMA API "dma_get_merge_boundary". This function returns the DMA merge boundary if the DMA layer can merge the segments. This patch also adds the implementation for a new dma_map_ops pointer. Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Reviewed-by: Simon Horman <horms+renesas@verge.net.au> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-03mmc: queue: use bigger segments if DMA MAP layer can merge the segmentsYoshihiro Shimoda2-3/+33
When the max_segs of a mmc host is smaller than 512, the mmc subsystem tries to use 512 segments if DMA MAP layer can merge the segments, and then the mmc subsystem exposes such information to the block layer by using blk_queue_can_use_dma_map_merging(). Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Reviewed-by: Simon Horman <horms+renesas@verge.net.au> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-03block: add a helper function to merge the segmentsYoshihiro Shimoda2-0/+25
This patch adds a helper function whether a queue can merge the segments by the DMA MAP layer (e.g. via IOMMU). Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Simon Horman <horms+renesas@verge.net.au Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-08-29MIPS: document mixing "slightly different CCAs"Christoph Hellwig1-0/+7
Based on an email from Paul Burton, quoting section 4.8 "Cacheability and Coherency Attributes and Access Types" of "MIPS Architecture Volume 1: Introduction to the MIPS32 Architecture" (MD00080, revision 6.01). Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Paul Burton <paul.burton@mips.com>
2019-08-29arm64: document the choice of page attributes for pgprot_dmacoherentChristoph Hellwig1-0/+8
Based on an email from Will Deacon. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Will Deacon <will@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com>
2019-08-29dma-mapping: make dma_atomic_pool_init self-containedChristoph Hellwig6-28/+14
The memory allocated for the atomic pool needs to have the same mapping attributes that we use for remapping, so use pgprot_dmacoherent instead of open coding it. Also deduct a suitable zone to allocate the memory from based on the presence of the DMA zones. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-08-29dma-mapping: remove arch_dma_mmap_pgprotChristoph Hellwig13-34/+35
arch_dma_mmap_pgprot is used for two things: 1) to override the "normal" uncached page attributes for mapping memory coherent to devices that can't snoop the CPU caches 2) to provide the special DMA_ATTR_WRITE_COMBINE semantics on older arm systems and some mips platforms Replace one with the pgprot_dmacoherent macro that is already provided by arm and much simpler to use, and lift the DMA_ATTR_WRITE_COMBINE handling to common code with an explicit arch opt-in. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k Acked-by: Paul Burton <paul.burton@mips.com> # mips
2019-08-26arm-nommu: remove the unused pgprot_dmacoherent defineChristoph Hellwig1-1/+0
Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-08-26unicore32: remove the unused pgprot_dmacoherent defineChristoph Hellwig1-2/+0
Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-08-25Linux 5.3-rc6Linus Torvalds1-1/+1
2019-08-25Merge tag 'auxdisplay-for-linus-v5.3-rc7' of git://github.com/ojeda/linuxLinus Torvalds1-2/+2
Pull auxdisplay cleanup from Miguel Ojeda: "Make ht16k33_fb_fix and ht16k33_fb_var constant (Nishka Dasgupta)" * tag 'auxdisplay-for-linus-v5.3-rc7' of git://github.com/ojeda/linux: auxdisplay: ht16k33: Make ht16k33_fb_fix and ht16k33_fb_var constant
2019-08-25Merge tag 'for-linus-5.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/umlLinus Torvalds3-12/+20
Pull UML fix from Richard Weinberger: "Fix time travel mode" * tag 'for-linus-5.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml: um: fix time travel mode
2019-08-25Merge tag 'for-linus-5.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifsLinus Torvalds4-8/+5
Pull UBIFS and JFFS2 fixes from Richard Weinberger: "UBIFS: - Don't block too long in writeback_inodes_sb() - Fix for a possible overrun of the log head - Fix double unlock in orphan_delete() JFFS2: - Remove C++ style from UAPI header and unbreak picky toolchains" * tag 'for-linus-5.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs: ubifs: Limit the number of pages in shrink_liability ubifs: Correctly initialize c->min_log_bytes ubifs: Fix double unlock around orphan_delete() jffs2: Remove C++ style comments from uapi header
2019-08-25Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds9-33/+227
Pull x86 fixes from Thomas Gleixner: "A few fixes for x86: - Fix a boot regression caused by the recent bootparam sanitizing change, which escaped the attention of all people who reviewed that code. - Address a boot problem on machines with broken E820 tables caused by an underflow which ended up placing the trampoline start at physical address 0. - Handle machines which do not advertise a legacy timer of any form, but need calibration of the local APIC timer gracefully by making the calibration routine independent from the tick interrupt. Marked for stable as well as there seems to be quite some new laptops rolled out which expose this. - Clear the RDRAND CPUID bit on AMD family 15h and 16h CPUs which are affected by broken firmware which does not initialize RDRAND correctly after resume. Add a command line parameter to override this for machine which either do not use suspend/resume or have a fixed BIOS. Unfortunately there is no way to detect this on boot, so the only safe decision is to turn it off by default. - Prevent RFLAGS from being clobbers in CALL_NOSPEC on 32bit which caused fast KVM instruction emulation to break. - Explain the Intel CPU model naming convention so that the repeating discussions come to an end" * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/retpoline: Don't clobber RFLAGS during CALL_NOSPEC on i386 x86/boot: Fix boot regression caused by bootparam sanitizing x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h x86/boot/compressed/64: Fix boot on machines with broken E820 table x86/apic: Handle missing global clockevent gracefully x86/cpu: Explain Intel model naming convention
2019-08-25Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds3-9/+23
Pull timekeeping fix from Thomas Gleixner: "A single fix for a regression caused by the generic VDSO implementation where a math overflow causes CLOCK_BOOTTIME to become a random number generator" * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: timekeeping/vsyscall: Prevent math overflow in BOOTTIME update
2019-08-25Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds1-1/+4
Pull scheduler fix from Thomas Gleixner: "Handle the worker management in situations where a task is scheduled out on a PI lock contention correctly and schedule a new worker if possible" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/core: Schedule new worker even if PI-blocked
2019-08-25Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds2-5/+5
Pull perf fixes from Thomas Gleixner: "Two small fixes for kprobes and perf: - Prevent a deadlock in kprobe_optimizer() causes by reverse lock ordering - Fix a comment typo" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: kprobes: Fix potential deadlock in kprobe_optimizer() perf/x86: Fix typo in comment
2019-08-25Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds1-1/+14
Pull irq fix from Thomas Gleixner: "A single fix for a imbalanced kobject operation in the irq decriptor code which was unearthed by the new warnings in the kobject code" * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: genirq: Properly pair kobject_del() with kobject_add()
2019-08-25Merge branch 'akpm' (patches from Andrew)Linus Torvalds9-36/+260
Mergr misc fixes from Andrew Morton: "11 fixes" Mostly VM fixes, one psi polling fix, and one parisc build fix. * emailed patches from Andrew Morton <akpm@linux-foundation.org>: mm/kasan: fix false positive invalid-free reports with CONFIG_KASAN_SW_TAGS=y mm/zsmalloc.c: fix race condition in zs_destroy_pool mm/zsmalloc.c: migration can leave pages in ZS_EMPTY indefinitely mm, page_owner: handle THP splits correctly userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx psi: get poll_work to run when calling poll syscall next time mm: memcontrol: flush percpu vmevents before releasing memcg mm: memcontrol: flush percpu vmstats before releasing memcg parisc: fix compilation errrors mm, page_alloc: move_freepages should not examine struct page of reserved memory mm/z3fold.c: fix race between migration and destruction
2019-08-24Merge tag 'dma-mapping-5.3-5' of git://git.infradead.org/users/hch/dma-mappingLinus Torvalds6-15/+19
Pull dma-mapping fixes from Christoph Hellwig: "Two fixes for regressions in this merge window: - select the Kconfig symbols for the noncoherent dma arch helpers on arm if swiotlb is selected, not just for LPAE to not break then Xen build, that uses swiotlb indirectly through swiotlb-xen - fix the page allocator fallback in dma_alloc_contiguous if the CMA allocation fails" * tag 'dma-mapping-5.3-5' of git://git.infradead.org/users/hch/dma-mapping: dma-direct: fix zone selection after an unaddressable CMA allocation arm: select the dma-noncoherent symbols for all swiotlb builds
2019-08-24mm/kasan: fix false positive invalid-free reports with CONFIG_KASAN_SW_TAGS=yAndrey Ryabinin1-2/+8
The code like this: ptr = kmalloc(size, GFP_KERNEL); page = virt_to_page(ptr); offset = offset_in_page(ptr); kfree(page_address(page) + offset); may produce false-positive invalid-free reports on the kernel with CONFIG_KASAN_SW_TAGS=y. In the example above we lose the original tag assigned to 'ptr', so kfree() gets the pointer with 0xFF tag. In kfree() we check that 0xFF tag is different from the tag in shadow hence print false report. Instead of just comparing tags, do the following: 1) Check that shadow doesn't contain KASAN_TAG_INVALID. Otherwise it's double-free and it doesn't matter what tag the pointer have. 2) If pointer tag is different from 0xFF, make sure that tag in the shadow is the same as in the pointer. Link: http://lkml.kernel.org/r/20190819172540.19581-1-aryabinin@virtuozzo.com Fixes: 7f94ffbc4c6a ("kasan: add hooks implementation for tag-based mode") Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reported-by: Walter Wu <walter-zh.wu@mediatek.com> Reported-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Andrey Konovalov <andreyknvl@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-24mm/zsmalloc.c: fix race condition in zs_destroy_poolHenry Burns1-2/+59
In zs_destroy_pool() we call flush_work(&pool->free_work). However, we have no guarantee that migration isn't happening in the background at that time. Since migration can't directly free pages, it relies on free_work being scheduled to free the pages. But there's nothing preventing an in-progress migrate from queuing the work *after* zs_unregister_migration() has called flush_work(). Which would mean pages still pointing at the inode when we free it. Since we know at destroy time all objects should be free, no new migrations can come in (since zs_page_isolate() fails for fully-free zspages). This means it is sufficient to track a "# isolated zspages" count by class, and have the destroy logic ensure all such pages have drained before proceeding. Keeping that state under the class spinlock keeps the logic straightforward. In this case a memory leak could lead to an eventual crash if compaction hits the leaked page. This crash would only occur if people are changing their zswap backend at runtime (which eventually starts destruction). Link: http://lkml.kernel.org/r/20190809181751.219326-2-henryburns@google.com Fixes: 48b4800a1c6a ("zsmalloc: page migration support") Signed-off-by: Henry Burns <henryburns@google.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Henry Burns <henrywolfeburns@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Jonathan Adams <jwadams@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-24mm/zsmalloc.c: migration can leave pages in ZS_EMPTY indefinitelyHenry Burns1-4/+15
In zs_page_migrate() we call putback_zspage() after we have finished migrating all pages in this zspage. However, the return value is ignored. If a zs_free() races in between zs_page_isolate() and zs_page_migrate(), freeing the last object in the zspage, putback_zspage() will leave the page in ZS_EMPTY for potentially an unbounded amount of time. To fix this, we need to do the same thing as zs_page_putback() does: schedule free_work to occur. To avoid duplicated code, move the sequence to a new putback_zspage_deferred() function which both zs_page_migrate() and zs_page_putback() call. Link: http://lkml.kernel.org/r/20190809181751.219326-1-henryburns@google.com Fixes: 48b4800a1c6a ("zsmalloc: page migration support") Signed-off-by: Henry Burns <henryburns@google.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Henry Burns <henrywolfeburns@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Jonathan Adams <jwadams@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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