Re: [PATCH v2 2/2] selftests/mm: verify droppable mappings cannot be locked

[Mark Brown]

On Tue, Mar 10, 2026 at 08:58:21AM -0700, Anthony Yznaga wrote:

> Verify that a mapping created with MAP_DROPPABLE cannot be locked
> via mlock(), and that it will not be locked if it's created after
> mlockall(MCL_FUTURE).

I'm seeing a regression in -next on 32 bit arm which bisects to this
patch:

# # ----------------------
# # running ./mlock2-tests
# # ----------------------
# # TAP version 13
# # 1..15
# # ok 1 test_mlock_lock: Locked
# # ok 2 test_mlock_lock: Unlocked
# # ok 3 test_mlock_onfault: VMA marked for lock on fault
# # ok 4 VMA open lock after fault
# # ok 5 test_munlockall0: Locked memory area
# # ok 6 test_munlockall0: No locked memory
# # ok 7 test_munlockall1: VMA marked for lock on fault
# # ok 8 test_munlockall1: Unlocked
# # ok 9 test_munlockall1: Locked
# # ok 10 test_munlockall1: No locked memory
# # ok 11 VMA with present pages is not marked lock on fault
# # ok 12 test_vma_management call_mlock 1
# # ok 13 test_vma_management call_mlock 0
# # Bail out! mmap error: Unknown error 524# Planned tests != run tests (15 != 13)
# # # Totals: pass:13 fail:0 xfail:0 xpass:0 skip:0 error:0
# # [FAIL]
# not ok 2 mlock2-tests # exit=1

Full log:

   https://lava.sirena.org.uk/scheduler/job/2617389#L2426

Previously the end of that test looked like:

# # ok 12 test_vma_management call_mlock 1
# # ok 13 test_vma_management call_mlock 0
# # # Totals: pass:13 fail:0 xfail:0 xpass:0 skip:0 error:0

The new tests do:

> +/*
> + * Droppable memory should not be lockable.
> + */
> +static void test_mlock_droppable(void)
> +{
> +	char *map;
> +	unsigned long page_size = getpagesize();
> +
> +	/*
> +	 * Ensure MCL_FUTURE is not set.
> +	 */
> +	if (mlockall(MCL_CURRENT))
> +		ksft_exit_fail_msg("mlockall(MCL_CURRENT): %s\n", strerror(errno));
> +	if (munlockall())
> +		ksft_exit_fail_msg("munlockall() %s\n", strerror(errno));
> +
> +	map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
> +		   MAP_ANONYMOUS | MAP_DROPPABLE, -1, 0);
> +	if (map == MAP_FAILED)
> +		ksft_exit_fail_msg("mmap error: %s", strerror(errno));

All these failures which cause the entire test program to immediately
die seem exceessively strong...

Full bisect log:

# bad: [cf7c3c02fdd0dfccf4d6611714273dcb538af2cb] Add linux-next specific files for 20260330
# good: [a010730e610019b6d010ec43ce737cb59a37809d] Merge branch 'for-linux-next-fixes' of https://gitlab.freedesktop.org/drm/misc/kernel.git
# good: [9be71d462c33b1a00acfa4ab8f0f5332ed592817] firmware: cs_dsp: Simplify suppressing log messages during KUnit testing
# good: [7b3f8db159f710d432c4edc024fcefa9e62e8b4b] ASoC: fsl_xcvr: add bitcount and timestamp controls
# good: [8fc5c7895185d1119ae76b509892a1d14e0bd483] ASoC: wm_adsp: Combine some similar code in firmware file search
# good: [981b080a79724738882b0af1c5bb7ade30d94f24] spi: fsl-qspi: Use reinit_completion() for repeated operations
# good: [ed0313223ce6514dbd39c049e25f702980d7e3cc] ASoC: codecs: wcd9335: Remove potential undefined behavior in wcd9335_slimbus_irq()
# good: [97af961568c8682c44506c9ad4b26c8a5455ec1d] ASoC: cs35l56: Put OTP register defines in correct address order
# good: [0a208adefecb287d22321054470d4619cb303839] ASoC: cs42l43: Add support for the B variant
# good: [a8075ada4a341ce58ebf8bef0188cefe6c2f6487] ASoC: ti: davinci-mcasp: improve aux_div selection for mid-range dividers
# good: [aa3d0c93a333182e887426366a4f3e5f06ee0d83] regulator: max20411: show failure on register
# good: [b1ef855c62601ed4de2c4b0ff75a075877e3dac8] regmap: Simplify devres handling
# good: [e7662bced2e98ffa2c572126677deb9cf55d43b3] regcache: Move HW readback after cache initialisation
# good: [ef0b4783afc211a4b120e72b5a57f3d0340a9981] ASoC: cs35l56: KUnit tests for reading speaker ID from host GPIOs
# good: [96f06d055ca03d1dfb5830fd07ff6eadbd66264c] spi: dt-bindings: mpfs-spi: remove clock-names
# good: [2adac914c72b6cb5aba2612f49050c82aecd498e] ASoC: cs35l56-test: Add test cases without onchip pulls defined
# good: [f48e7a246a567e3764112e2463274c479d95cd96] ASoC: soc-core: Use guard()/scoped_guard() for mutex lock
# good: [9891b52ba12e9d5fed5901b6b5f6e0cdcd424390] regcache: Factor out regcache_hw_exit() helper
# good: [e84141846decb77d2826e553318a608b256804e5] regulator: pf9453: Allow shared IRQ
# good: [9ab637ac5d3826606947f4e861107da958eda324] regcache: Amend printf() specifiers when printing registers
# good: [34b4fc44e4f904fbb81335d53163ffdcb0180000] ASoC: soc_sdw_utils: remove index from sdca codec name
# good: [da37bfe76b5b4ccc01ed8132215098e20d78e5f3] ASoC: cs42xx8: add error checks for constraints in TDM mode
# good: [d3b693a13b39bce16e284e1c737874966b3a96de] spi: spi-mem: clean up kernel-doc in spi-mem.h
# good: [06dba254de95b16e7793224d29daa5195de2e581] ASoC: dt-bindings: nvidia,tegra-audio-max9808x: document additional board pins
# good: [1696fad8b259a2d46e51cd6e17e4bcdbe02279fa] ASoC: sti: use managed regmap_field allocations
# good: [17c6bf433742e0c1ff5ce175145877c0194e4a7a] ASoC: cs35l45: Hibernate wm_adsp on runtime suspend
# good: [2974aa42e6696a1d95b727d677dc01a71af5b998] ASoC: remove snd_soc_pcm_subclass
# good: [501efdcb3b3ab099fc0ce2f6e668b1c4095dd476] ASoC: SDCA: Pull the Q7.8 volume helpers out of soc-ops
# good: [d90c0f78379454d51a428e312ac6db573060185c] regulator: cpcap-regulator: add support for Mot regulators
# good: [5c74a008ffc62fc57a041602b4517519c8bf9436] firmware: cs_dsp: Mark KUnit test suites KUNIT_SPEED_SLOW
# good: [260c3fff1fefc570d8f23e87953e181d7d248861] ASoC: cs-amp-lib-test: Stop including platform_device.h
# good: [7c12f6ead4672cb08b74e6f6115eb04dca8ccfa4] spi: tegra210-quad: Add runtime autosuspend support
# good: [37983fad7f3ef296fa0504c8e945987459dc5487] regmap: define cleanup helper for regmap_field
# good: [e02902dd493bf9c9b05353c761737ac514ad7a5c] spi: add devm_spi_new_ancillary_device()
# good: [ada32396f90951e12465224c04742607ca56a982] ASoC: SDCA: Add CS47L47 to class driver
# good: [507a071d9868cb60e4e76f8a06fc8eb014f59ae4] spi: pxa2xx: use min() instead of min_t()
# good: [5ebc20921b7fff9feb44de465448e17a382c9965] ASoC: tas2552: Allow audio enable GPIO to sleep
# good: [fed6e5084894373d76270cad4a32eb6479ad8247] spi: atcspi200: Remove redundant assignment to .owner
# good: [c2bcf62ca75c541ec4297e6ff02a68ddc2e02029] regcache: Split regcache_count_cacheable_registers() helper
# good: [171b3663f33e1efdc97f5112f49be10b47b20fa8] ASoC: codecs: aw88261: Add firmware-name support
# good: [bf122191473e26a8f195308b1ba924c98424c8e1] ASoC: rt5677-spi: Add SPI device ID matching table
# good: [fbb4c52ccdcb4a612d2b7f800aa57090eeee16d7] regulator: spacemit-p1: Update supply names
# good: [0556bb42a84ee391a2145ddba86756f9747bc27f] regulator: pf0900: Make regu_irqs variable static const
# good: [d075cef4af6327a5de4bee7bf77591e3201e54f4] ASoC: simple-card-utils: add sysclk ordering support
# good: [78dfbd4ad0be9f51de7b9a19388809254aeccd26] ASoC: Add quirk for Lecoo Bellator N176
git bisect start 'cf7c3c02fdd0dfccf4d6611714273dcb538af2cb' 'a010730e610019b6d010ec43ce737cb59a37809d' '9be71d462c33b1a00acfa4ab8f0f5332ed592817' '7b3f8db159f710d432c4edc024fcefa9e62e8b4b' '8fc5c7895185d1119ae76b509892a1d14e0bd483' '981b080a79724738882b0af1c5bb7ade30d94f24' 'ed0313223ce6514dbd39c049e25f702980d7e3cc' '97af961568c8682c44506c9ad4b26c8a5455ec1d' '0a208adefecb287d22321054470d4619cb303839' 'a8075ada4a341ce58ebf8bef0188cefe6c2f6487' 'aa3d0c93a333182e887426366a4f3e5f06ee0d83' 'b1ef855c62601ed4de2c4b0ff75a075877e3dac8' 'e7662bced2e98ffa2c572126677deb9cf55d43b3' 'ef0b4783afc211a4b120e72b5a57f3d0340a9981' '96f06d055ca03d1dfb5830fd07ff6eadbd66264c' '2adac914c72b6cb5aba2612f49050c82aecd498e' 'f48e7a246a567e3764112e2463274c479d95cd96' '9891b52ba12e9d5fed5901b6b5f6e0cdcd424390' 'e84141846decb77d2826e553318a608b256804e5' '9ab637ac5d3826606947f4e861107da958eda324' '34b4fc44e4f904fbb81335d53163ffdcb0180000' 'da37bfe76b5b4ccc01ed8132215098e20d78e5f3' 'd3b693a13b39bce16e284e1c737874966b3a96de' '06dba254de95b16e7793224d29daa5195de2e581' '1696fad8b259a2d46e51cd6e17e4bcdbe02279fa' '17c6bf433742e0c1ff5ce175145877c0194e4a7a' '2974aa42e6696a1d95b727d677dc01a71af5b998' '501efdcb3b3ab099fc0ce2f6e668b1c4095dd476' 'd90c0f78379454d51a428e312ac6db573060185c' '5c74a008ffc62fc57a041602b4517519c8bf9436' '260c3fff1fefc570d8f23e87953e181d7d248861' '7c12f6ead4672cb08b74e6f6115eb04dca8ccfa4' '37983fad7f3ef296fa0504c8e945987459dc5487' 'e02902dd493bf9c9b05353c761737ac514ad7a5c' 'ada32396f90951e12465224c04742607ca56a982' '507a071d9868cb60e4e76f8a06fc8eb014f59ae4' '5ebc20921b7fff9feb44de465448e17a382c9965' 'fed6e5084894373d76270cad4a32eb6479ad8247' 'c2bcf62ca75c541ec4297e6ff02a68ddc2e02029' '171b3663f33e1efdc97f5112f49be10b47b20fa8' 'bf122191473e26a8f195308b1ba924c98424c8e1' 'fbb4c52ccdcb4a612d2b7f800aa57090eeee16d7' '0556bb42a84ee391a2145ddba86756f9747bc27f' 'd075cef4af6327a5de4bee7bf77591e3201e54f4' '78dfbd4ad0be9f51de7b9a19388809254aeccd26'
# test job: [9be71d462c33b1a00acfa4ab8f0f5332ed592817] https://lava.sirena.org.uk/scheduler/job/2548958
# test job: [7b3f8db159f710d432c4edc024fcefa9e62e8b4b] https://lava.sirena.org.uk/scheduler/job/2548203
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# test job: [ed0313223ce6514dbd39c049e25f702980d7e3cc] https://lava.sirena.org.uk/scheduler/job/2544912
# test job: [97af961568c8682c44506c9ad4b26c8a5455ec1d] https://lava.sirena.org.uk/scheduler/job/2543844
# test job: [0a208adefecb287d22321054470d4619cb303839] https://lava.sirena.org.uk/scheduler/job/2542900
# test job: [a8075ada4a341ce58ebf8bef0188cefe6c2f6487] https://lava.sirena.org.uk/scheduler/job/2541074
# test job: [aa3d0c93a333182e887426366a4f3e5f06ee0d83] https://lava.sirena.org.uk/scheduler/job/2531465
# test job: [b1ef855c62601ed4de2c4b0ff75a075877e3dac8] https://lava.sirena.org.uk/scheduler/job/2531932
# test job: [e7662bced2e98ffa2c572126677deb9cf55d43b3] https://lava.sirena.org.uk/scheduler/job/2530760
# test job: [ef0b4783afc211a4b120e72b5a57f3d0340a9981] https://lava.sirena.org.uk/scheduler/job/2530588
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# test job: [9891b52ba12e9d5fed5901b6b5f6e0cdcd424390] https://lava.sirena.org.uk/scheduler/job/2522227
# test job: [e84141846decb77d2826e553318a608b256804e5] https://lava.sirena.org.uk/scheduler/job/2516954
# test job: [9ab637ac5d3826606947f4e861107da958eda324] https://lava.sirena.org.uk/scheduler/job/2516270
# test job: [34b4fc44e4f904fbb81335d53163ffdcb0180000] https://lava.sirena.org.uk/scheduler/job/2513176
# test job: [da37bfe76b5b4ccc01ed8132215098e20d78e5f3] https://lava.sirena.org.uk/scheduler/job/2511945
# test job: [d3b693a13b39bce16e284e1c737874966b3a96de] https://lava.sirena.org.uk/scheduler/job/2511939
# test job: [06dba254de95b16e7793224d29daa5195de2e581] https://lava.sirena.org.uk/scheduler/job/2513148
# test job: [1696fad8b259a2d46e51cd6e17e4bcdbe02279fa] https://lava.sirena.org.uk/scheduler/job/2513461
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# test job: [d90c0f78379454d51a428e312ac6db573060185c] https://lava.sirena.org.uk/scheduler/job/2500276
# test job: [5c74a008ffc62fc57a041602b4517519c8bf9436] https://lava.sirena.org.uk/scheduler/job/2496475
# test job: [260c3fff1fefc570d8f23e87953e181d7d248861] https://lava.sirena.org.uk/scheduler/job/2494070
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# test job: [37983fad7f3ef296fa0504c8e945987459dc5487] https://lava.sirena.org.uk/scheduler/job/2489226
# test job: [e02902dd493bf9c9b05353c761737ac514ad7a5c] https://lava.sirena.org.uk/scheduler/job/2489635
# test job: [ada32396f90951e12465224c04742607ca56a982] https://lava.sirena.org.uk/scheduler/job/2489222
# test job: [507a071d9868cb60e4e76f8a06fc8eb014f59ae4] https://lava.sirena.org.uk/scheduler/job/2486412
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# test job: [c2bcf62ca75c541ec4297e6ff02a68ddc2e02029] https://lava.sirena.org.uk/scheduler/job/2482354
# test job: [171b3663f33e1efdc97f5112f49be10b47b20fa8] https://lava.sirena.org.uk/scheduler/job/2483216
# test job: [bf122191473e26a8f195308b1ba924c98424c8e1] https://lava.sirena.org.uk/scheduler/job/2483327
# test job: [fbb4c52ccdcb4a612d2b7f800aa57090eeee16d7] https://lava.sirena.org.uk/scheduler/job/2482378
# test job: [0556bb42a84ee391a2145ddba86756f9747bc27f] https://lava.sirena.org.uk/scheduler/job/2482373
# test job: [d075cef4af6327a5de4bee7bf77591e3201e54f4] https://lava.sirena.org.uk/scheduler/job/2482695
# test job: [78dfbd4ad0be9f51de7b9a19388809254aeccd26] https://lava.sirena.org.uk/scheduler/job/2482880
# test job: [cf7c3c02fdd0dfccf4d6611714273dcb538af2cb] https://lava.sirena.org.uk/scheduler/job/2617389
# bad: [cf7c3c02fdd0dfccf4d6611714273dcb538af2cb] Add linux-next specific files for 20260330
git bisect bad cf7c3c02fdd0dfccf4d6611714273dcb538af2cb
# test job: [38b3953f6750a4200d3b37a5bfbee8370fdbd504] https://lava.sirena.org.uk/scheduler/job/2617530
# bad: [38b3953f6750a4200d3b37a5bfbee8370fdbd504] Merge branch 'main' of https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
git bisect bad 38b3953f6750a4200d3b37a5bfbee8370fdbd504
# test job: [a4fb128b640bfc9a123150836109eba580ad1209] https://lava.sirena.org.uk/scheduler/job/2617626
# bad: [a4fb128b640bfc9a123150836109eba580ad1209] Merge branch 'xtensa-for-next' of https://github.com/jcmvbkbc/linux-xtensa.git
git bisect bad a4fb128b640bfc9a123150836109eba580ad1209
# test job: [1da8729e2823f81c215a5e08191f3bbc64da48a7] https://lava.sirena.org.uk/scheduler/job/2617703
# bad: [1da8729e2823f81c215a5e08191f3bbc64da48a7] Merge branch 'soc_fsl' of https://git.kernel.org/pub/scm/linux/kernel/git/chleroy/linux.git
git bisect bad 1da8729e2823f81c215a5e08191f3bbc64da48a7
# test job: [fd706c02d6ce8331b3979ab082653aa2dda6f820] https://lava.sirena.org.uk/scheduler/job/2617851
# bad: [fd706c02d6ce8331b3979ab082653aa2dda6f820] Merge branch 'mm-unstable' of https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
git bisect bad fd706c02d6ce8331b3979ab082653aa2dda6f820
# test job: [d1bebf23909c97a1d31422b62493c7c70cfafa06] https://lava.sirena.org.uk/scheduler/job/2617901
# bad: [d1bebf23909c97a1d31422b62493c7c70cfafa06] mm: prepare to move subsection_map_init() to mm/sparse-vmemmap.c
git bisect bad d1bebf23909c97a1d31422b62493c7c70cfafa06
# test job: [4bcefc23862b988ce7a9fe7dcba2f6ab0c9b5fa7] https://lava.sirena.org.uk/scheduler/job/2618076
# good: [4bcefc23862b988ce7a9fe7dcba2f6ab0c9b5fa7] mm/vmalloc: fix incorrect size reporting on allocation failure
git bisect good 4bcefc23862b988ce7a9fe7dcba2f6ab0c9b5fa7
# test job: [798a6c72ebedf11da7b46e21b458f39d7787aba7] https://lava.sirena.org.uk/scheduler/job/2618272
# good: [798a6c72ebedf11da7b46e21b458f39d7787aba7] Docs/admin-guide/mm/damn/lru_sort: fix intervals autotune parameter name
git bisect good 798a6c72ebedf11da7b46e21b458f39d7787aba7
# test job: [75af4a7b19c295127790e42469e1863148795c26] https://lava.sirena.org.uk/scheduler/job/2618319
# bad: [75af4a7b19c295127790e42469e1863148795c26] selftests/mm: pagemap_ioctl: remove hungarian notation
git bisect bad 75af4a7b19c295127790e42469e1863148795c26
# test job: [6235dbcce97f5b164efe6725dc6002b646943e1d] https://lava.sirena.org.uk/scheduler/job/2618397
# bad: [6235dbcce97f5b164efe6725dc6002b646943e1d] selftests/mm: verify droppable mappings cannot be locked
git bisect bad 6235dbcce97f5b164efe6725dc6002b646943e1d
# test job: [c0fbc73a20da662edc4d603ed3d4b80503b55478] https://lava.sirena.org.uk/scheduler/job/2618493
# good: [c0fbc73a20da662edc4d603ed3d4b80503b55478] kho: make sure preservations do not span multiple NUMA nodes
git bisect good c0fbc73a20da662edc4d603ed3d4b80503b55478
# test job: [e2b717936d1a3f6b1f179fd03ce8e6a8f4ebc6ee] https://lava.sirena.org.uk/scheduler/job/2618533
# good: [e2b717936d1a3f6b1f179fd03ce8e6a8f4ebc6ee] zram: drop ->num_active_comps
git bisect good e2b717936d1a3f6b1f179fd03ce8e6a8f4ebc6ee
# test job: [4fd453f1644669bdd79177da31c29d32353d57f7] https://lava.sirena.org.uk/scheduler/job/2618566
# good: [4fd453f1644669bdd79177da31c29d32353d57f7] zram: remove chained recompression
git bisect good 4fd453f1644669bdd79177da31c29d32353d57f7
# test job: [5435ba164b0dd162e1a2fb47ab2d3f5cd70905f9] https://lava.sirena.org.uk/scheduler/job/2618612
# good: [5435ba164b0dd162e1a2fb47ab2d3f5cd70905f9] mm: prevent droppable mappings from being locked
git bisect good 5435ba164b0dd162e1a2fb47ab2d3f5cd70905f9
# first bad commit: [6235dbcce97f5b164efe6725dc6002b646943e1d] selftests/mm: verify droppable mappings cannot be locked

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