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    Subject[PATCH 4.19 032/287] dma-debug: change allocation mode from GFP_NOWAIT to GFP_ATIOMIC
    Date
    From: Mikulas Patocka <mpatocka@redhat.com>

    [ Upstream commit 84bc4f1dbbbb5f8aa68706a96711dccb28b518e5 ]

    We observed the error "cacheline tracking ENOMEM, dma-debug disabled"
    during a light system load (copying some files). The reason for this error
    is that the dma_active_cacheline radix tree uses GFP_NOWAIT allocation -
    so it can't access the emergency memory reserves and it fails as soon as
    anybody reaches the watermark.

    This patch changes GFP_NOWAIT to GFP_ATOMIC, so that it can access the
    emergency memory reserves.

    Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
    Signed-off-by: Christoph Hellwig <hch@lst.de>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/dma/debug.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
    index 9c9a5b12f92f..7c6cd00d0fca 100644
    --- a/kernel/dma/debug.c
    +++ b/kernel/dma/debug.c
    @@ -469,7 +469,7 @@ void debug_dma_dump_mappings(struct device *dev)
    * At any time debug_dma_assert_idle() can be called to trigger a
    * warning if any cachelines in the given page are in the active set.
    */
    -static RADIX_TREE(dma_active_cacheline, GFP_NOWAIT);
    +static RADIX_TREE(dma_active_cacheline, GFP_ATOMIC);
    static DEFINE_SPINLOCK(radix_lock);
    #define ACTIVE_CACHELINE_MAX_OVERLAP ((1 << RADIX_TREE_MAX_TAGS) - 1)
    #define CACHELINE_PER_PAGE_SHIFT (PAGE_SHIFT - L1_CACHE_SHIFT)
    --
    2.35.1


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