[PATCH v2 2/2] scsi: target: rd: Don't invoke the OOM killer for ramdisk pages

[Sanan Hasanov <sanan.hasanou@gmail.com>]

From: Sanan Hasanov <sanan.hasanov@ucf.edu>

rd_allocate_sgl_table() allocates the ramdisk's backing memory one page
at a time with GFP_KERNEL. When the requested ramdisk is larger than the
memory that can be freed, these allocations do not fail but invoke the
OOM killer instead. The pages are not charged to any task, so the OOM
killer keeps killing unrelated processes, and may panic the system once
nothing is left to kill, while the configfs write continues allocating.

Use __GFP_RETRY_MAYFAIL so that the allocation fails once reclaim can
make no more progress. rd_allocate_sgl_table() already handles failure
by returning -ENOMEM, and the caller then releases the pages allocated
so far. Add __GFP_NOWARN since the driver logs its own error.

Signed-off-by: Sanan Hasanov <sanan.hasanov@ucf.edu>
---
 drivers/target/target_core_rd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c
index 97c63b122..46698300e 100644
--- a/drivers/target/target_core_rd.c
+++ b/drivers/target/target_core_rd.c
@@ -150,7 +150,8 @@ static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *
 						- 1;
 
 		for (j = 0; j < sg_per_table; j++) {
-			pg = alloc_pages(GFP_KERNEL, 0);
+			pg = alloc_pages(GFP_KERNEL | __GFP_RETRY_MAYFAIL |
+					 __GFP_NOWARN, 0);
 			if (!pg) {
 				pr_err("Unable to allocate scatterlist"
 					" pages for struct rd_dev_sg_table\n");
-- 
2.48.1