Commit 0eccce86 authored by Damien Le Moal's avatar Damien Le Moal Committed by Martin K. Petersen
Browse files

scsi: target: tcmu: Prevent memory reclaim recursion 

Prevent recursion into the IO path under low memory conditions by using
GFP_NOIO in place of GFP_KERNEL when allocating a new command with
tcmu_alloc_cmd() and user ring space with tcmu_get_empty_block().

Link: https://lore.kernel.org/r/20191108082901.417950-1-damien.lemoal@wdc.com


Reported-by: default avatarMasato Suzuki <masato.suzuki@wdc.com>
Signed-off-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Acked-by: default avatarMike Christie <mchristi@redhat.com>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 9237f04e

drivers/target/target_core_user.c

+3 −3
Original line number Diff line number Diff line
@@ -499,7 +499,7 @@ static inline bool tcmu_get_empty_block(struct tcmu_dev *udev, 
			schedule_delayed_work(&tcmu_unmap_work, 0);



		/* try to get new page from the mm */

		page = alloc_page(GFP_KERNEL);

		page = alloc_page(GFP_NOIO);

		if (!page)

			goto err_alloc;
@@ -573,7 +573,7 @@ static struct tcmu_cmd *tcmu_alloc_cmd(struct se_cmd *se_cmd) 
	struct tcmu_dev *udev = TCMU_DEV(se_dev);

	struct tcmu_cmd *tcmu_cmd;



	tcmu_cmd = kmem_cache_zalloc(tcmu_cmd_cache, GFP_KERNEL);

	tcmu_cmd = kmem_cache_zalloc(tcmu_cmd_cache, GFP_NOIO);

	if (!tcmu_cmd)

		return NULL;
@@ -584,7 +584,7 @@ static struct tcmu_cmd *tcmu_alloc_cmd(struct se_cmd *se_cmd) 
	tcmu_cmd_reset_dbi_cur(tcmu_cmd);

	tcmu_cmd->dbi_cnt = tcmu_cmd_get_block_cnt(tcmu_cmd);

	tcmu_cmd->dbi = kcalloc(tcmu_cmd->dbi_cnt, sizeof(uint32_t),

				GFP_KERNEL);

				GFP_NOIO);

	if (!tcmu_cmd->dbi) {

		kmem_cache_free(tcmu_cmd_cache, tcmu_cmd);

		return NULL;