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Dan Williams
d2c997c0f1
Catch cases where extent unmap operations encounter pages that are pinned / busy. Typically this is pinned pages that are under active dma. This warning is a canary for potential data corruption as truncated blocks could be allocated to a new file while the device is still performing i/o. Here is an example of a collision that this implementation catches: WARNING: CPU: 2 PID: 1286 at fs/dax.c:343 dax_disassociate_entry+0x55/0x80 [..] Call Trace: __dax_invalidate_mapping_entry+0x6c/0xf0 dax_delete_mapping_entry+0xf/0x20 truncate_exceptional_pvec_entries.part.12+0x1af/0x200 truncate_inode_pages_range+0x268/0x970 ? tlb_gather_mmu+0x10/0x20 ? up_write+0x1c/0x40 ? unmap_mapping_range+0x73/0x140 xfs_free_file_space+0x1b6/0x5b0 [xfs] ? xfs_file_fallocate+0x7f/0x320 [xfs] ? down_write_nested+0x40/0x70 ? xfs_ilock+0x21d/0x2f0 [xfs] xfs_file_fallocate+0x162/0x320 [xfs] ? rcu_read_lock_sched_held+0x3f/0x70 ? rcu_sync_lockdep_assert+0x2a/0x50 ? __sb_start_write+0xd0/0x1b0 ? vfs_fallocate+0x20c/0x270 vfs_fallocate+0x154/0x270 SyS_fallocate+0x43/0x80 entry_SYSCALL_64_fastpath+0x1f/0x96 Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.