From 3fab4d9e08aa1471c5c34bf7fdc2632bf4a7d494 Mon Sep 17 00:00:00 2001 From: Paul Dagnelie Date: Tue, 25 Jun 2019 12:50:38 -0700 Subject: zdb -vvvvv on ztest pool dies with "out of memory" ztest creates some extremely large files as part of its operation. When zdb tries to dump a large enough file, it can run out of memory or spend an extremely long time attempting to print millions or billions of uint64_ts. We cap the amount of data from a uint64 object that we are willing to read and print. Reviewed-by: Don Brady Reviewed-by: Brian Behlendorf Signed-off-by: Paul Dagnelie External-issue: DLPX-53814 Closes #8947 --- cmd/zdb/zdb.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) (limited to 'cmd') diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c index 969c8f1b7..e0ea07280 100644 --- a/cmd/zdb/zdb.c +++ b/cmd/zdb/zdb.c @@ -424,23 +424,35 @@ static void dump_uint64(objset_t *os, uint64_t object, void *data, size_t size) { uint64_t *arr; - + uint64_t oursize; if (dump_opt['d'] < 6) return; + if (data == NULL) { dmu_object_info_t doi; VERIFY0(dmu_object_info(os, object, &doi)); size = doi.doi_max_offset; - arr = kmem_alloc(size, KM_SLEEP); + /* + * We cap the size at 1 mebibyte here to prevent + * allocation failures and nigh-infinite printing if the + * object is extremely large. + */ + oursize = MIN(size, 1 << 20); + arr = kmem_alloc(oursize, KM_SLEEP); - int err = dmu_read(os, object, 0, size, arr, 0); + int err = dmu_read(os, object, 0, oursize, arr, 0); if (err != 0) { (void) printf("got error %u from dmu_read\n", err); - kmem_free(arr, size); + kmem_free(arr, oursize); return; } } else { + /* + * Even though the allocation is already done in this code path, + * we still cap the size to prevent excessive printing. + */ + oursize = MIN(size, 1 << 20); arr = data; } @@ -450,16 +462,18 @@ dump_uint64(objset_t *os, uint64_t object, void *data, size_t size) } (void) printf("\t\t[%0llx", (u_longlong_t)arr[0]); - for (size_t i = 1; i * sizeof (uint64_t) < size; i++) { + for (size_t i = 1; i * sizeof (uint64_t) < oursize; i++) { if (i % 4 != 0) (void) printf(", %0llx", (u_longlong_t)arr[i]); else (void) printf(",\n\t\t%0llx", (u_longlong_t)arr[i]); } + if (oursize != size) + (void) printf(", ... "); (void) printf("]\n"); if (data == NULL) - kmem_free(arr, size); + kmem_free(arr, oursize); } /*ARGSUSED*/ -- cgit v1.2.3