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    Subject[PATCH 5.6 233/254] xen/blkfront: fix memory allocation flags in blkfront_setup_indirect()
    Date
    From: Juergen Gross <jgross@suse.com>

    commit 3a169c0be75b59dd85d159493634870cdec6d3c4 upstream.

    Commit 1d5c76e664333 ("xen-blkfront: switch kcalloc to kvcalloc for
    large array allocation") didn't fix the issue it was meant to, as the
    flags for allocating the memory are GFP_NOIO, which will lead the
    memory allocation falling back to kmalloc().

    So instead of GFP_NOIO use GFP_KERNEL and do all the memory allocation
    in blkfront_setup_indirect() in a memalloc_noio_{save,restore} section.

    Fixes: 1d5c76e664333 ("xen-blkfront: switch kcalloc to kvcalloc for large array allocation")
    Cc: stable@vger.kernel.org
    Signed-off-by: Juergen Gross <jgross@suse.com>
    Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    Acked-by: Roger Pau Monné <roger.pau@citrix.com>
    Link: https://lore.kernel.org/r/20200403090034.8753-1-jgross@suse.com
    Signed-off-by: Juergen Gross <jgross@suse.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/block/xen-blkfront.c | 17 ++++++++++++-----
    1 file changed, 12 insertions(+), 5 deletions(-)

    --- a/drivers/block/xen-blkfront.c
    +++ b/drivers/block/xen-blkfront.c
    @@ -47,6 +47,7 @@
    #include <linux/bitmap.h>
    #include <linux/list.h>
    #include <linux/workqueue.h>
    +#include <linux/sched/mm.h>

    #include <xen/xen.h>
    #include <xen/xenbus.h>
    @@ -2189,10 +2190,12 @@ static void blkfront_setup_discard(struc

    static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
    {
    - unsigned int psegs, grants;
    + unsigned int psegs, grants, memflags;
    int err, i;
    struct blkfront_info *info = rinfo->dev_info;

    + memflags = memalloc_noio_save();
    +
    if (info->max_indirect_segments == 0) {
    if (!HAS_EXTRA_REQ)
    grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
    @@ -2224,7 +2227,7 @@ static int blkfront_setup_indirect(struc

    BUG_ON(!list_empty(&rinfo->indirect_pages));
    for (i = 0; i < num; i++) {
    - struct page *indirect_page = alloc_page(GFP_NOIO);
    + struct page *indirect_page = alloc_page(GFP_KERNEL);
    if (!indirect_page)
    goto out_of_memory;
    list_add(&indirect_page->lru, &rinfo->indirect_pages);
    @@ -2235,15 +2238,15 @@ static int blkfront_setup_indirect(struc
    rinfo->shadow[i].grants_used =
    kvcalloc(grants,
    sizeof(rinfo->shadow[i].grants_used[0]),
    - GFP_NOIO);
    + GFP_KERNEL);
    rinfo->shadow[i].sg = kvcalloc(psegs,
    sizeof(rinfo->shadow[i].sg[0]),
    - GFP_NOIO);
    + GFP_KERNEL);
    if (info->max_indirect_segments)
    rinfo->shadow[i].indirect_grants =
    kvcalloc(INDIRECT_GREFS(grants),
    sizeof(rinfo->shadow[i].indirect_grants[0]),
    - GFP_NOIO);
    + GFP_KERNEL);
    if ((rinfo->shadow[i].grants_used == NULL) ||
    (rinfo->shadow[i].sg == NULL) ||
    (info->max_indirect_segments &&
    @@ -2252,6 +2255,7 @@ static int blkfront_setup_indirect(struc
    sg_init_table(rinfo->shadow[i].sg, psegs);
    }

    + memalloc_noio_restore(memflags);

    return 0;

    @@ -2271,6 +2275,9 @@ out_of_memory:
    __free_page(indirect_page);
    }
    }
    +
    + memalloc_noio_restore(memflags);
    +
    return -ENOMEM;
    }


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