Long-running operations in the kernel should:
o not monopolize the CPU
o abort when asked
Put voluntary preemption points in ckpt_kread, ckpt_kwrite, and the
VMA-walking checkpoint code. At the same points, return an error if a
fatal signal is pending; callers of these functions are supposed to be
checking return values.
Signed-off-by: Nathan Lynch <ntl@xxxxxxxxx>
---
kernel/checkpoint/sys.c | 10 ++++++++++
mm/checkpoint.c | 7 +++++++
2 files changed, 17 insertions(+), 0 deletions(-)
diff --git a/kernel/checkpoint/sys.c b/kernel/checkpoint/sys.c
index b761ec0..04e6277 100644
--- a/kernel/checkpoint/sys.c
+++ b/kernel/checkpoint/sys.c
@@ -72,6 +72,11 @@ int ckpt_kwrite(struct ckpt_ctx *ctx, void *addr, size_t count)
if (ckpt_test_error(ctx))
return ckpt_get_error(ctx);
+ if (fatal_signal_pending(current))
+ return -EINTR;
+
+ cond_resched();
+
ret = _ckpt_kwrite(ctx->file, addr, count);
if (ret < 0)
return ret;
@@ -103,6 +108,11 @@ int ckpt_kread(struct ckpt_ctx *ctx, void *addr, size_t count)
if (ckpt_test_error(ctx))
return ckpt_get_error(ctx);
+ if (fatal_signal_pending(current))
+ return -EINTR;
+
+ cond_resched();
+
ret = _ckpt_kread(ctx->file, addr, count);
if (ret < 0)
return ret;
diff --git a/mm/checkpoint.c b/mm/checkpoint.c
index 70300e8..6732a2e 100644
--- a/mm/checkpoint.c
+++ b/mm/checkpoint.c
@@ -310,6 +310,13 @@ static int vma_fill_pgarr(struct ckpt_ctx *ctx,
while (addr < end) {
struct page *page;
+ if (fatal_signal_pending(current)) {
+ cnt = -EINTR;
+ goto out;
+ }
+
+ cond_resched();
+
if (vma)
page = consider_private_page(vma, addr);
else
--
1.7.3.2
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