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From 0066b862bb3a09f39295abd5d972a53ac8dc1555 Mon Sep 17 00:00:00 2001
From: Peter Bergin <peter@berginkonsult.se>
Date: Wed, 19 Sep 2018 15:12:31 +0200
Subject: [PATCH] rpm/rpmio.c: restrict virtual memory usage if limit set
A solution to avoid OOM situation when the virtual memory is restricted
for a user (ulimit -v). As the lzopen_internal function is run in parallel
one instance per CPU thread the available virtual memory is limited per
CPU thread.
Upstream-Status: Pending [merge of multithreading patches to upstream]
Signed-off-by: Peter Bergin <peter@berginkonsult.se>
---
rpmio/rpmio.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/rpmio/rpmio.c b/rpmio/rpmio.c
index e051c98..b3c56b6 100644
--- a/rpmio/rpmio.c
+++ b/rpmio/rpmio.c
@@ -845,6 +845,40 @@ static LZFILE *lzopen_internal(const char *mode, int fd, int xz)
}
#endif
+ struct rlimit virtual_memory;
+ getrlimit(RLIMIT_AS, &virtual_memory);
+ if (virtual_memory.rlim_cur != RLIM_INFINITY) {
+ const uint64_t virtual_memlimit = virtual_memory.rlim_cur;
+ const uint64_t virtual_memlimit_per_cpu_thread =
+ virtual_memlimit / lzma_cputhreads();
+ uint64_t memory_usage_virt;
+ rpmlog(RPMLOG_NOTICE, "XZ: virtual memory restricted to %lu and "
+ "per CPU thread %lu\n", virtual_memlimit, virtual_memlimit_per_cpu_thread);
+ /* keep reducing the number of compression threads until memory
+ usage falls below the limit per CPU thread*/
+ while ((memory_usage_virt = lzma_stream_encoder_mt_memusage(&mt_options)) >
+ virtual_memlimit_per_cpu_thread) {
+ /* If number of threads goes down to zero lzma_stream_encoder will
+ * will return UINT64_MAX. We must check here to avoid an infinite loop.
+ * If we get into situation that one thread requires more virtual memory
+ * than available we set one thread, print error message and try anyway. */
+ if (--mt_options.threads == 0) {
+ mt_options.threads = 1;
+ rpmlog(RPMLOG_WARNING,
+ "XZ: Could not adjust number of threads to get below "
+ "virtual memory limit %lu. usage %lu\n",
+ virtual_memlimit_per_cpu_thread, memory_usage_virt);
+ break;
+ }
+ }
+ if (threads != (int)mt_options.threads)
+ rpmlog(RPMLOG_NOTICE,
+ "XZ: Adjusted the number of threads from %d to %d to not "
+ "exceed the memory usage limit of %lu bytes\n",
+ threads, mt_options.threads, virtual_memlimit);
+
+ }
+
ret = lzma_stream_encoder_mt(&lzfile->strm, &mt_options);
}
#endif
--
2.7.4
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