The XPFO [1] patchset may unmap pages from physmap if they happened to be destined for userspace. If such a page is unmapped, it needs to be remapped. Rather than test if a page is in the highmem/xpfo unmapped state, Christoph suggested [2] that we simply always map the page.
Suggested-by: Christoph Hellwig <h...@infradead.org> Signed-off-by: Tycho Andersen <ty...@docker.com> CC: Juerg Haefliger <juerg.haefli...@hpe.com> CC: Tejun Heo <t...@kernel.org> [1]: https://lkml.org/lkml/2016/11/4/245 [2]: https://lkml.org/lkml/2016/11/4/253 --- I don't understand all the factors at play here, so thoughts are definitely welcome. --- drivers/ata/libata-sff.c | 50 +++++++++++++++++------------------------------- 1 file changed, 18 insertions(+), 32 deletions(-) diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c index 2bd92dc..8da2572 100644 --- a/drivers/ata/libata-sff.c +++ b/drivers/ata/libata-sff.c @@ -703,6 +703,7 @@ static void ata_pio_sector(struct ata_queued_cmd *qc) struct page *page; unsigned int offset; unsigned char *buf; + unsigned long flags; if (qc->curbytes == qc->nbytes - qc->sect_size) ap->hsm_task_state = HSM_ST_LAST; @@ -716,24 +717,16 @@ static void ata_pio_sector(struct ata_queued_cmd *qc) DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read"); - if (PageHighMem(page)) { - unsigned long flags; - - /* FIXME: use a bounce buffer */ - local_irq_save(flags); - buf = kmap_atomic(page); + /* FIXME: use a bounce buffer */ + local_irq_save(flags); + buf = kmap_atomic(page); - /* do the actual data transfer */ - ap->ops->sff_data_xfer(qc, buf + offset, qc->sect_size, - do_write); + /* do the actual data transfer */ + ap->ops->sff_data_xfer(qc, buf + offset, qc->sect_size, + do_write); - kunmap_atomic(buf); - local_irq_restore(flags); - } else { - buf = page_address(page); - ap->ops->sff_data_xfer(qc, buf + offset, qc->sect_size, - do_write); - } + kunmap_atomic(buf); + local_irq_restore(flags); if (!do_write && !PageSlab(page)) flush_dcache_page(page); @@ -836,6 +829,7 @@ static int __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes) struct page *page; unsigned char *buf; unsigned int offset, count, consumed; + unsigned long flags; next_sg: sg = qc->cursg; @@ -861,24 +855,16 @@ static int __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes) DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read"); - if (PageHighMem(page)) { - unsigned long flags; - - /* FIXME: use bounce buffer */ - local_irq_save(flags); - buf = kmap_atomic(page); + /* FIXME: use bounce buffer */ + local_irq_save(flags); + buf = kmap_atomic(page); - /* do the actual data transfer */ - consumed = ap->ops->sff_data_xfer(qc, buf + offset, - count, rw); + /* do the actual data transfer */ + consumed = ap->ops->sff_data_xfer(qc, buf + offset, + count, rw); - kunmap_atomic(buf); - local_irq_restore(flags); - } else { - buf = page_address(page); - consumed = ap->ops->sff_data_xfer(qc, buf + offset, - count, rw); - } + kunmap_atomic(buf); + local_irq_restore(flags); bytes -= min(bytes, consumed); qc->curbytes += count; -- 2.9.3
