March 2024 - Linux-stable-mirror

[PATCH v2 2/7] btrfs: reduce the log level for btrfs_dev_stat_inc_and_print()

by Qu Wenruo

Currently when we increase the device statistics, it would always lead to an error message in the kernel log. However this output is mostly duplicated with the existing ones: - For scrub operations We always have the following messages: * "fixed up error at logical %llu" * "unable to fixup (regular) error at logical %llu" So no matter if the corruption is repaired or not, it scrub would output an error message to indicate the problem. - For non-scrub read operations We also have the following messages: * "csum failed root %lld inode %llu off %llu" for data csum mismatch * "bad (tree block start|fsid|tree block level)" for metadata * "read error corrected: ino %llu off %llu" for repaired data/metadata So the error message from btrfs_dev_stat_inc_and_print() is duplicated. The real usage for the btrfs device statistics is for some user space daemon to check if there is any new errors, acting like some checks on SMART, thus we don't really need/want those messages in dmesg. This patch would reduce the log level to debug (disabled by default) for btrfs_dev_stat_inc_and_print(). For users really want to utilize btrfs devices statistics, they should go check "btrfs device stats" periodically, and we should focus the kernel error messages to more important things. CC: stable(a)vger.kernel.org Reviewed-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: Qu Wenruo <wqu(a)suse.com> --- fs/btrfs/volumes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index e49935a54da0..126145950ed3 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -7828,7 +7828,7 @@ void btrfs_dev_stat_inc_and_print(struct btrfs_device *dev, int index) if (!dev->dev_stats_valid) return; - btrfs_err_rl_in_rcu(dev->fs_info, + btrfs_debug_rl_in_rcu(dev->fs_info, "bdev %s errs: wr %u, rd %u, flush %u, corrupt %u, gen %u", btrfs_dev_name(dev), btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_WRITE_ERRS), -- 2.44.0

11 months

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[PATCH v2] selftests/ftrace: Limit length in subsystem-enable tests

by Yuanhe Shu

While sched* events being traced and sched* events continuously happen, "[xx] event tracing - enable/disable with subsystem level files" would not stop as on some slower systems it seems to take forever. Select the first 100 lines of output would be enough to judge whether there are more than 3 types of sched events. Fixes: 815b18ea66d6 ("ftracetest: Add basic event tracing test cases") Cc: stable(a)vger.kernel.org Signed-off-by: Yuanhe Shu <xiangzao(a)linux.alibaba.com> --- .../selftests/ftrace/test.d/event/subsystem-enable.tc | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc b/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc index b1ede6249866..b7c8f29c09a9 100644 --- a/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc +++ b/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc @@ -18,7 +18,7 @@ echo 'sched:*' > set_event yield -count=`cat trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l` +count=`head -n 100 trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l` if [ $count -lt 3 ]; then fail "at least fork, exec and exit events should be recorded" fi @@ -29,7 +29,7 @@ echo 1 > events/sched/enable yield -count=`cat trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l` +count=`head -n 100 trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l` if [ $count -lt 3 ]; then fail "at least fork, exec and exit events should be recorded" fi @@ -40,7 +40,7 @@ echo 0 > events/sched/enable yield -count=`cat trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l` +count=`head -n 100 trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l` if [ $count -ne 0 ]; then fail "any of scheduler events should not be recorded" fi -- 2.39.3

11 months

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FAILED: patch "[PATCH] mm, vmscan: prevent infinite loop for costly GFP_NOIO |" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 803de9000f334b771afacb6ff3e78622916668b0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024032730-triceps-mustang-3ced@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: 803de9000f33 ("mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations") f98a497e1f16 ("mm: compaction: remove unnecessary is_via_compact_memory() checks") e8606320e9af ("mm: compaction: refactor __compaction_suitable()") fe573327ffb1 ("tracing: incorrect gfp_t conversion") cff387d6a294 ("mm: compaction: make compaction_zonelist_suitable return false when COMPACT_SUCCESS") 9353ffa6e9e9 ("kasan, page_alloc: allow skipping memory init for HW_TAGS") 53ae233c30a6 ("kasan, page_alloc: allow skipping unpoisoning for HW_TAGS") f49d9c5bb15c ("kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS") e9d0ca922816 ("kasan, page_alloc: rework kasan_unpoison_pages call site") 7e3cbba65de2 ("kasan, page_alloc: move kernel_init_free_pages in post_alloc_hook") 89b271163328 ("kasan, page_alloc: move SetPageSkipKASanPoison in post_alloc_hook") 9294b1281d0a ("kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook") b42090ae6f3a ("kasan, page_alloc: merge kasan_alloc_pages into post_alloc_hook") b8491b9052fe ("kasan, page_alloc: refactor init checks in post_alloc_hook") 1c0e5b24f117 ("kasan: only apply __GFP_ZEROTAGS when memory is zeroed") c82ce3195fd1 ("mm: clarify __GFP_ZEROTAGS comment") 7c13c163e036 ("kasan, page_alloc: merge kasan_free_pages into free_pages_prepare") 5b2c07138cbd ("kasan, page_alloc: move tag_clear_highpage out of kernel_init_free_pages") 94ae8b83fefc ("kasan, page_alloc: deduplicate should_skip_kasan_poison") 3bf03b9a0839 ("Merge branch 'akpm' (patches from Andrew)") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 803de9000f334b771afacb6ff3e78622916668b0 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka <vbabka(a)suse.cz> Date: Wed, 21 Feb 2024 12:43:58 +0100 Subject: [PATCH] mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations Sven reports an infinite loop in __alloc_pages_slowpath() for costly order __GFP_RETRY_MAYFAIL allocations that are also GFP_NOIO. Such combination can happen in a suspend/resume context where a GFP_KERNEL allocation can have __GFP_IO masked out via gfp_allowed_mask. Quoting Sven: 1. try to do a "costly" allocation (order > PAGE_ALLOC_COSTLY_ORDER) with __GFP_RETRY_MAYFAIL set. 2. page alloc's __alloc_pages_slowpath tries to get a page from the freelist. This fails because there is nothing free of that costly order. 3. page alloc tries to reclaim by calling __alloc_pages_direct_reclaim, which bails out because a zone is ready to be compacted; it pretends to have made a single page of progress. 4. page alloc tries to compact, but this always bails out early because __GFP_IO is not set (it's not passed by the snd allocator, and even if it were, we are suspending so the __GFP_IO flag would be cleared anyway). 5. page alloc believes reclaim progress was made (because of the pretense in item 3) and so it checks whether it should retry compaction. The compaction retry logic thinks it should try again, because: a) reclaim is needed because of the early bail-out in item 4 b) a zonelist is suitable for compaction 6. goto 2. indefinite stall. (end quote) The immediate root cause is confusing the COMPACT_SKIPPED returned from __alloc_pages_direct_compact() (step 4) due to lack of __GFP_IO to be indicating a lack of order-0 pages, and in step 5 evaluating that in should_compact_retry() as a reason to retry, before incrementing and limiting the number of retries. There are however other places that wrongly assume that compaction can happen while we lack __GFP_IO. To fix this, introduce gfp_compaction_allowed() to abstract the __GFP_IO evaluation and switch the open-coded test in try_to_compact_pages() to use it. Also use the new helper in: - compaction_ready(), which will make reclaim not bail out in step 3, so there's at least one attempt to actually reclaim, even if chances are small for a costly order - in_reclaim_compaction() which will make should_continue_reclaim() return false and we don't over-reclaim unnecessarily - in __alloc_pages_slowpath() to set a local variable can_compact, which is then used to avoid retrying reclaim/compaction for costly allocations (step 5) if we can't compact and also to skip the early compaction attempt that we do in some cases Link: https://lkml.kernel.org/r/20240221114357.13655-2-vbabka@suse.cz Fixes: 3250845d0526 ("Revert "mm, oom: prevent premature OOM killer invocation for high order request"") Signed-off-by: Vlastimil Babka <vbabka(a)suse.cz> Reported-by: Sven van Ashbrook <svenva(a)chromium.org> Closes: https://lore.kernel.org/all/CAG-rBihs_xMKb3wrMO1%2B-%2Bp4fowP9oy1pa_OTkfxBz… Tested-by: Karthikeyan Ramasubramanian <kramasub(a)chromium.org> Cc: Brian Geffon <bgeffon(a)google.com> Cc: Curtis Malainey <cujomalainey(a)chromium.org> Cc: Jaroslav Kysela <perex(a)perex.cz> Cc: Mel Gorman <mgorman(a)techsingularity.net> Cc: Michal Hocko <mhocko(a)kernel.org> Cc: Takashi Iwai <tiwai(a)suse.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/include/linux/gfp.h b/include/linux/gfp.h index de292a007138..e2a916cf29c4 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -353,6 +353,15 @@ static inline bool gfp_has_io_fs(gfp_t gfp) return (gfp & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS); } +/* + * Check if the gfp flags allow compaction - GFP_NOIO is a really + * tricky context because the migration might require IO. + */ +static inline bool gfp_compaction_allowed(gfp_t gfp_mask) +{ + return IS_ENABLED(CONFIG_COMPACTION) && (gfp_mask & __GFP_IO); +} + extern gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma); #ifdef CONFIG_CONTIG_ALLOC diff --git a/mm/compaction.c b/mm/compaction.c index 4add68d40e8d..b961db601df4 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -2723,16 +2723,11 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, unsigned int alloc_flags, const struct alloc_context *ac, enum compact_priority prio, struct page **capture) { - int may_perform_io = (__force int)(gfp_mask & __GFP_IO); struct zoneref *z; struct zone *zone; enum compact_result rc = COMPACT_SKIPPED; - /* - * Check if the GFP flags allow compaction - GFP_NOIO is really - * tricky context because the migration might require IO - */ - if (!may_perform_io) + if (!gfp_compaction_allowed(gfp_mask)) return COMPACT_SKIPPED; trace_mm_compaction_try_to_compact_pages(order, gfp_mask, prio); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 150d4f23b010..a663202045dc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4041,6 +4041,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, struct alloc_context *ac) { bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM; + bool can_compact = gfp_compaction_allowed(gfp_mask); const bool costly_order = order > PAGE_ALLOC_COSTLY_ORDER; struct page *page = NULL; unsigned int alloc_flags; @@ -4111,7 +4112,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, * Don't try this for allocations that are allowed to ignore * watermarks, as the ALLOC_NO_WATERMARKS attempt didn't yet happen. */ - if (can_direct_reclaim && + if (can_direct_reclaim && can_compact && (costly_order || (order > 0 && ac->migratetype != MIGRATE_MOVABLE)) && !gfp_pfmemalloc_allowed(gfp_mask)) { @@ -4209,9 +4210,10 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, /* * Do not retry costly high order allocations unless they are - * __GFP_RETRY_MAYFAIL + * __GFP_RETRY_MAYFAIL and we can compact */ - if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL)) + if (costly_order && (!can_compact || + !(gfp_mask & __GFP_RETRY_MAYFAIL))) goto nopage; if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags, @@ -4224,7 +4226,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, * implementation of the compaction depends on the sufficient amount * of free memory (see __compaction_suitable) */ - if (did_some_progress > 0 && + if (did_some_progress > 0 && can_compact && should_compact_retry(ac, order, alloc_flags, compact_result, &compact_priority, &compaction_retries)) diff --git a/mm/vmscan.c b/mm/vmscan.c index 4f9c854ce6cc..4255619a1a31 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -5753,7 +5753,7 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) /* Use reclaim/compaction for costly allocs or under memory pressure */ static bool in_reclaim_compaction(struct scan_control *sc) { - if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && + if (gfp_compaction_allowed(sc->gfp_mask) && sc->order && (sc->order > PAGE_ALLOC_COSTLY_ORDER || sc->priority < DEF_PRIORITY - 2)) return true; @@ -5998,6 +5998,9 @@ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) { unsigned long watermark; + if (!gfp_compaction_allowed(sc->gfp_mask)) + return false; + /* Allocation can already succeed, nothing to do */ if (zone_watermark_ok(zone, sc->order, min_wmark_pages(zone), sc->reclaim_idx, 0))

11 months

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FAILED: patch "[PATCH] mm, vmscan: prevent infinite loop for costly GFP_NOIO |" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 803de9000f334b771afacb6ff3e78622916668b0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024032727-pastel-sincerity-a986@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: 803de9000f33 ("mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations") f98a497e1f16 ("mm: compaction: remove unnecessary is_via_compact_memory() checks") e8606320e9af ("mm: compaction: refactor __compaction_suitable()") fe573327ffb1 ("tracing: incorrect gfp_t conversion") cff387d6a294 ("mm: compaction: make compaction_zonelist_suitable return false when COMPACT_SUCCESS") 9353ffa6e9e9 ("kasan, page_alloc: allow skipping memory init for HW_TAGS") 53ae233c30a6 ("kasan, page_alloc: allow skipping unpoisoning for HW_TAGS") f49d9c5bb15c ("kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS") e9d0ca922816 ("kasan, page_alloc: rework kasan_unpoison_pages call site") 7e3cbba65de2 ("kasan, page_alloc: move kernel_init_free_pages in post_alloc_hook") 89b271163328 ("kasan, page_alloc: move SetPageSkipKASanPoison in post_alloc_hook") 9294b1281d0a ("kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook") b42090ae6f3a ("kasan, page_alloc: merge kasan_alloc_pages into post_alloc_hook") b8491b9052fe ("kasan, page_alloc: refactor init checks in post_alloc_hook") 1c0e5b24f117 ("kasan: only apply __GFP_ZEROTAGS when memory is zeroed") c82ce3195fd1 ("mm: clarify __GFP_ZEROTAGS comment") 7c13c163e036 ("kasan, page_alloc: merge kasan_free_pages into free_pages_prepare") 5b2c07138cbd ("kasan, page_alloc: move tag_clear_highpage out of kernel_init_free_pages") 94ae8b83fefc ("kasan, page_alloc: deduplicate should_skip_kasan_poison") 3bf03b9a0839 ("Merge branch 'akpm' (patches from Andrew)") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 803de9000f334b771afacb6ff3e78622916668b0 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka <vbabka(a)suse.cz> Date: Wed, 21 Feb 2024 12:43:58 +0100 Subject: [PATCH] mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations Sven reports an infinite loop in __alloc_pages_slowpath() for costly order __GFP_RETRY_MAYFAIL allocations that are also GFP_NOIO. Such combination can happen in a suspend/resume context where a GFP_KERNEL allocation can have __GFP_IO masked out via gfp_allowed_mask. Quoting Sven: 1. try to do a "costly" allocation (order > PAGE_ALLOC_COSTLY_ORDER) with __GFP_RETRY_MAYFAIL set. 2. page alloc's __alloc_pages_slowpath tries to get a page from the freelist. This fails because there is nothing free of that costly order. 3. page alloc tries to reclaim by calling __alloc_pages_direct_reclaim, which bails out because a zone is ready to be compacted; it pretends to have made a single page of progress. 4. page alloc tries to compact, but this always bails out early because __GFP_IO is not set (it's not passed by the snd allocator, and even if it were, we are suspending so the __GFP_IO flag would be cleared anyway). 5. page alloc believes reclaim progress was made (because of the pretense in item 3) and so it checks whether it should retry compaction. The compaction retry logic thinks it should try again, because: a) reclaim is needed because of the early bail-out in item 4 b) a zonelist is suitable for compaction 6. goto 2. indefinite stall. (end quote) The immediate root cause is confusing the COMPACT_SKIPPED returned from __alloc_pages_direct_compact() (step 4) due to lack of __GFP_IO to be indicating a lack of order-0 pages, and in step 5 evaluating that in should_compact_retry() as a reason to retry, before incrementing and limiting the number of retries. There are however other places that wrongly assume that compaction can happen while we lack __GFP_IO. To fix this, introduce gfp_compaction_allowed() to abstract the __GFP_IO evaluation and switch the open-coded test in try_to_compact_pages() to use it. Also use the new helper in: - compaction_ready(), which will make reclaim not bail out in step 3, so there's at least one attempt to actually reclaim, even if chances are small for a costly order - in_reclaim_compaction() which will make should_continue_reclaim() return false and we don't over-reclaim unnecessarily - in __alloc_pages_slowpath() to set a local variable can_compact, which is then used to avoid retrying reclaim/compaction for costly allocations (step 5) if we can't compact and also to skip the early compaction attempt that we do in some cases Link: https://lkml.kernel.org/r/20240221114357.13655-2-vbabka@suse.cz Fixes: 3250845d0526 ("Revert "mm, oom: prevent premature OOM killer invocation for high order request"") Signed-off-by: Vlastimil Babka <vbabka(a)suse.cz> Reported-by: Sven van Ashbrook <svenva(a)chromium.org> Closes: https://lore.kernel.org/all/CAG-rBihs_xMKb3wrMO1%2B-%2Bp4fowP9oy1pa_OTkfxBz… Tested-by: Karthikeyan Ramasubramanian <kramasub(a)chromium.org> Cc: Brian Geffon <bgeffon(a)google.com> Cc: Curtis Malainey <cujomalainey(a)chromium.org> Cc: Jaroslav Kysela <perex(a)perex.cz> Cc: Mel Gorman <mgorman(a)techsingularity.net> Cc: Michal Hocko <mhocko(a)kernel.org> Cc: Takashi Iwai <tiwai(a)suse.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/include/linux/gfp.h b/include/linux/gfp.h index de292a007138..e2a916cf29c4 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -353,6 +353,15 @@ static inline bool gfp_has_io_fs(gfp_t gfp) return (gfp & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS); } +/* + * Check if the gfp flags allow compaction - GFP_NOIO is a really + * tricky context because the migration might require IO. + */ +static inline bool gfp_compaction_allowed(gfp_t gfp_mask) +{ + return IS_ENABLED(CONFIG_COMPACTION) && (gfp_mask & __GFP_IO); +} + extern gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma); #ifdef CONFIG_CONTIG_ALLOC diff --git a/mm/compaction.c b/mm/compaction.c index 4add68d40e8d..b961db601df4 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -2723,16 +2723,11 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, unsigned int alloc_flags, const struct alloc_context *ac, enum compact_priority prio, struct page **capture) { - int may_perform_io = (__force int)(gfp_mask & __GFP_IO); struct zoneref *z; struct zone *zone; enum compact_result rc = COMPACT_SKIPPED; - /* - * Check if the GFP flags allow compaction - GFP_NOIO is really - * tricky context because the migration might require IO - */ - if (!may_perform_io) + if (!gfp_compaction_allowed(gfp_mask)) return COMPACT_SKIPPED; trace_mm_compaction_try_to_compact_pages(order, gfp_mask, prio); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 150d4f23b010..a663202045dc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4041,6 +4041,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, struct alloc_context *ac) { bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM; + bool can_compact = gfp_compaction_allowed(gfp_mask); const bool costly_order = order > PAGE_ALLOC_COSTLY_ORDER; struct page *page = NULL; unsigned int alloc_flags; @@ -4111,7 +4112,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, * Don't try this for allocations that are allowed to ignore * watermarks, as the ALLOC_NO_WATERMARKS attempt didn't yet happen. */ - if (can_direct_reclaim && + if (can_direct_reclaim && can_compact && (costly_order || (order > 0 && ac->migratetype != MIGRATE_MOVABLE)) && !gfp_pfmemalloc_allowed(gfp_mask)) { @@ -4209,9 +4210,10 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, /* * Do not retry costly high order allocations unless they are - * __GFP_RETRY_MAYFAIL + * __GFP_RETRY_MAYFAIL and we can compact */ - if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL)) + if (costly_order && (!can_compact || + !(gfp_mask & __GFP_RETRY_MAYFAIL))) goto nopage; if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags, @@ -4224,7 +4226,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, * implementation of the compaction depends on the sufficient amount * of free memory (see __compaction_suitable) */ - if (did_some_progress > 0 && + if (did_some_progress > 0 && can_compact && should_compact_retry(ac, order, alloc_flags, compact_result, &compact_priority, &compaction_retries)) diff --git a/mm/vmscan.c b/mm/vmscan.c index 4f9c854ce6cc..4255619a1a31 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -5753,7 +5753,7 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) /* Use reclaim/compaction for costly allocs or under memory pressure */ static bool in_reclaim_compaction(struct scan_control *sc) { - if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && + if (gfp_compaction_allowed(sc->gfp_mask) && sc->order && (sc->order > PAGE_ALLOC_COSTLY_ORDER || sc->priority < DEF_PRIORITY - 2)) return true; @@ -5998,6 +5998,9 @@ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) { unsigned long watermark; + if (!gfp_compaction_allowed(sc->gfp_mask)) + return false; + /* Allocation can already succeed, nothing to do */ if (zone_watermark_ok(zone, sc->order, min_wmark_pages(zone), sc->reclaim_idx, 0))

11 months

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FAILED: patch "[PATCH] mm, vmscan: prevent infinite loop for costly GFP_NOIO |" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 803de9000f334b771afacb6ff3e78622916668b0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024032725-amigo-dental-d3bd@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: 803de9000f33 ("mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations") f98a497e1f16 ("mm: compaction: remove unnecessary is_via_compact_memory() checks") e8606320e9af ("mm: compaction: refactor __compaction_suitable()") fe573327ffb1 ("tracing: incorrect gfp_t conversion") cff387d6a294 ("mm: compaction: make compaction_zonelist_suitable return false when COMPACT_SUCCESS") 9353ffa6e9e9 ("kasan, page_alloc: allow skipping memory init for HW_TAGS") 53ae233c30a6 ("kasan, page_alloc: allow skipping unpoisoning for HW_TAGS") f49d9c5bb15c ("kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS") e9d0ca922816 ("kasan, page_alloc: rework kasan_unpoison_pages call site") 7e3cbba65de2 ("kasan, page_alloc: move kernel_init_free_pages in post_alloc_hook") 89b271163328 ("kasan, page_alloc: move SetPageSkipKASanPoison in post_alloc_hook") 9294b1281d0a ("kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook") b42090ae6f3a ("kasan, page_alloc: merge kasan_alloc_pages into post_alloc_hook") b8491b9052fe ("kasan, page_alloc: refactor init checks in post_alloc_hook") 1c0e5b24f117 ("kasan: only apply __GFP_ZEROTAGS when memory is zeroed") c82ce3195fd1 ("mm: clarify __GFP_ZEROTAGS comment") 7c13c163e036 ("kasan, page_alloc: merge kasan_free_pages into free_pages_prepare") 5b2c07138cbd ("kasan, page_alloc: move tag_clear_highpage out of kernel_init_free_pages") 94ae8b83fefc ("kasan, page_alloc: deduplicate should_skip_kasan_poison") 3bf03b9a0839 ("Merge branch 'akpm' (patches from Andrew)") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 803de9000f334b771afacb6ff3e78622916668b0 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka <vbabka(a)suse.cz> Date: Wed, 21 Feb 2024 12:43:58 +0100 Subject: [PATCH] mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations Sven reports an infinite loop in __alloc_pages_slowpath() for costly order __GFP_RETRY_MAYFAIL allocations that are also GFP_NOIO. Such combination can happen in a suspend/resume context where a GFP_KERNEL allocation can have __GFP_IO masked out via gfp_allowed_mask. Quoting Sven: 1. try to do a "costly" allocation (order > PAGE_ALLOC_COSTLY_ORDER) with __GFP_RETRY_MAYFAIL set. 2. page alloc's __alloc_pages_slowpath tries to get a page from the freelist. This fails because there is nothing free of that costly order. 3. page alloc tries to reclaim by calling __alloc_pages_direct_reclaim, which bails out because a zone is ready to be compacted; it pretends to have made a single page of progress. 4. page alloc tries to compact, but this always bails out early because __GFP_IO is not set (it's not passed by the snd allocator, and even if it were, we are suspending so the __GFP_IO flag would be cleared anyway). 5. page alloc believes reclaim progress was made (because of the pretense in item 3) and so it checks whether it should retry compaction. The compaction retry logic thinks it should try again, because: a) reclaim is needed because of the early bail-out in item 4 b) a zonelist is suitable for compaction 6. goto 2. indefinite stall. (end quote) The immediate root cause is confusing the COMPACT_SKIPPED returned from __alloc_pages_direct_compact() (step 4) due to lack of __GFP_IO to be indicating a lack of order-0 pages, and in step 5 evaluating that in should_compact_retry() as a reason to retry, before incrementing and limiting the number of retries. There are however other places that wrongly assume that compaction can happen while we lack __GFP_IO. To fix this, introduce gfp_compaction_allowed() to abstract the __GFP_IO evaluation and switch the open-coded test in try_to_compact_pages() to use it. Also use the new helper in: - compaction_ready(), which will make reclaim not bail out in step 3, so there's at least one attempt to actually reclaim, even if chances are small for a costly order - in_reclaim_compaction() which will make should_continue_reclaim() return false and we don't over-reclaim unnecessarily - in __alloc_pages_slowpath() to set a local variable can_compact, which is then used to avoid retrying reclaim/compaction for costly allocations (step 5) if we can't compact and also to skip the early compaction attempt that we do in some cases Link: https://lkml.kernel.org/r/20240221114357.13655-2-vbabka@suse.cz Fixes: 3250845d0526 ("Revert "mm, oom: prevent premature OOM killer invocation for high order request"") Signed-off-by: Vlastimil Babka <vbabka(a)suse.cz> Reported-by: Sven van Ashbrook <svenva(a)chromium.org> Closes: https://lore.kernel.org/all/CAG-rBihs_xMKb3wrMO1%2B-%2Bp4fowP9oy1pa_OTkfxBz… Tested-by: Karthikeyan Ramasubramanian <kramasub(a)chromium.org> Cc: Brian Geffon <bgeffon(a)google.com> Cc: Curtis Malainey <cujomalainey(a)chromium.org> Cc: Jaroslav Kysela <perex(a)perex.cz> Cc: Mel Gorman <mgorman(a)techsingularity.net> Cc: Michal Hocko <mhocko(a)kernel.org> Cc: Takashi Iwai <tiwai(a)suse.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/include/linux/gfp.h b/include/linux/gfp.h index de292a007138..e2a916cf29c4 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -353,6 +353,15 @@ static inline bool gfp_has_io_fs(gfp_t gfp) return (gfp & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS); } +/* + * Check if the gfp flags allow compaction - GFP_NOIO is a really + * tricky context because the migration might require IO. + */ +static inline bool gfp_compaction_allowed(gfp_t gfp_mask) +{ + return IS_ENABLED(CONFIG_COMPACTION) && (gfp_mask & __GFP_IO); +} + extern gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma); #ifdef CONFIG_CONTIG_ALLOC diff --git a/mm/compaction.c b/mm/compaction.c index 4add68d40e8d..b961db601df4 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -2723,16 +2723,11 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, unsigned int alloc_flags, const struct alloc_context *ac, enum compact_priority prio, struct page **capture) { - int may_perform_io = (__force int)(gfp_mask & __GFP_IO); struct zoneref *z; struct zone *zone; enum compact_result rc = COMPACT_SKIPPED; - /* - * Check if the GFP flags allow compaction - GFP_NOIO is really - * tricky context because the migration might require IO - */ - if (!may_perform_io) + if (!gfp_compaction_allowed(gfp_mask)) return COMPACT_SKIPPED; trace_mm_compaction_try_to_compact_pages(order, gfp_mask, prio); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 150d4f23b010..a663202045dc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4041,6 +4041,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, struct alloc_context *ac) { bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM; + bool can_compact = gfp_compaction_allowed(gfp_mask); const bool costly_order = order > PAGE_ALLOC_COSTLY_ORDER; struct page *page = NULL; unsigned int alloc_flags; @@ -4111,7 +4112,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, * Don't try this for allocations that are allowed to ignore * watermarks, as the ALLOC_NO_WATERMARKS attempt didn't yet happen. */ - if (can_direct_reclaim && + if (can_direct_reclaim && can_compact && (costly_order || (order > 0 && ac->migratetype != MIGRATE_MOVABLE)) && !gfp_pfmemalloc_allowed(gfp_mask)) { @@ -4209,9 +4210,10 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, /* * Do not retry costly high order allocations unless they are - * __GFP_RETRY_MAYFAIL + * __GFP_RETRY_MAYFAIL and we can compact */ - if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL)) + if (costly_order && (!can_compact || + !(gfp_mask & __GFP_RETRY_MAYFAIL))) goto nopage; if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags, @@ -4224,7 +4226,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, * implementation of the compaction depends on the sufficient amount * of free memory (see __compaction_suitable) */ - if (did_some_progress > 0 && + if (did_some_progress > 0 && can_compact && should_compact_retry(ac, order, alloc_flags, compact_result, &compact_priority, &compaction_retries)) diff --git a/mm/vmscan.c b/mm/vmscan.c index 4f9c854ce6cc..4255619a1a31 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -5753,7 +5753,7 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) /* Use reclaim/compaction for costly allocs or under memory pressure */ static bool in_reclaim_compaction(struct scan_control *sc) { - if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && + if (gfp_compaction_allowed(sc->gfp_mask) && sc->order && (sc->order > PAGE_ALLOC_COSTLY_ORDER || sc->priority < DEF_PRIORITY - 2)) return true; @@ -5998,6 +5998,9 @@ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) { unsigned long watermark; + if (!gfp_compaction_allowed(sc->gfp_mask)) + return false; + /* Allocation can already succeed, nothing to do */ if (zone_watermark_ok(zone, sc->order, min_wmark_pages(zone), sc->reclaim_idx, 0))

11 months

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[PATCH v2] usb: typec: tcpm: Correct the PDO counting in pd_set

by Kyle Tso

Off-by-one errors happen because nr_snk_pdo and nr_src_pdo are incorrectly added one. The index of the loop is equal to the number of PDOs to be updated when leaving the loop and it doesn't need to be added one. When doing the power negotiation, TCPM relies on the "nr_snk_pdo" as the size of the local sink PDO array to match the Source capabilities of the partner port. If the off-by-one overflow occurs, a wrong RDO might be sent and unexpected power transfer might happen such as over voltage or over current (than expected). "nr_src_pdo" is used to set the Rp level when the port is in Source role. It is also the array size of the local Source capabilities when filling up the buffer which will be sent as the Source PDOs (such as in Power Negotiation). If the off-by-one overflow occurs, a wrong Rp level might be set and wrong Source PDOs will be sent to the partner port. This could potentially cause over current or port resets. Fixes: cd099cde4ed2 ("usb: typec: tcpm: Support multiple capabilities") Cc: stable(a)vger.kernel.org Signed-off-by: Kyle Tso <kyletso(a)google.com> --- v1 -> v2: - update the commit message (adding the problems this patch solves) drivers/usb/typec/tcpm/tcpm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c index ae2b6c94482d..2464710ea0c8 100644 --- a/drivers/usb/typec/tcpm/tcpm.c +++ b/drivers/usb/typec/tcpm/tcpm.c @@ -6855,14 +6855,14 @@ static int tcpm_pd_set(struct typec_port *p, struct usb_power_delivery *pd) if (data->sink_desc.pdo[0]) { for (i = 0; i < PDO_MAX_OBJECTS && data->sink_desc.pdo[i]; i++) port->snk_pdo[i] = data->sink_desc.pdo[i]; - port->nr_snk_pdo = i + 1; + port->nr_snk_pdo = i; port->operating_snk_mw = data->operating_snk_mw; } if (data->source_desc.pdo[0]) { for (i = 0; i < PDO_MAX_OBJECTS && data->source_desc.pdo[i]; i++) port->snk_pdo[i] = data->source_desc.pdo[i]; - port->nr_src_pdo = i + 1; + port->nr_src_pdo = i; } switch (port->state) { -- 2.44.0.396.g6e790dbe36-goog

11 months

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[PATCH v4] x86/coco: Require seeding RNG with RDRAND on CoCo systems

by Jason A. Donenfeld

There are few uses of CoCo that don't rely on working cryptography and hence a working RNG. Unfortunately, the CoCo threat model means that the VM host cannot be trusted and may actively work against guests to extract secrets or manipulate computation. Since a malicious host can modify or observe nearly all inputs to guests, the only remaining source of entropy for CoCo guests is RDRAND. If RDRAND is broken -- due to CPU hardware fault -- the RNG as a whole is meant to gracefully continue on gathering entropy from other sources, but since there aren't other sources on CoCo, this is catastrophic. This is mostly a concern at boot time when initially seeding the RNG, as after that the consequences of a broken RDRAND are much more theoretical. So, try at boot to seed the RNG using 256 bits of RDRAND output. If this fails, panic(). This will also trigger if the system is booted without RDRAND, as RDRAND is essential for a safe CoCo boot. This patch is deliberately written to be "just a CoCo x86 driver feature" and not part of the RNG itself. Many device drivers and platforms have some desire to contribute something to the RNG, and add_device_randomness() is specifically meant for this purpose. Any driver can call this with seed data of any quality, or even garbage quality, and it can only possibly make the quality of the RNG better or have no effect, but can never make it worse. Rather than trying to build something into the core of the RNG, this patch interprets the particular CoCo issue as just a CoCo issue, and therefore separates this all out into driver (well, arch/platform) code. Cc: Borislav Petkov <bp(a)alien8.de> Cc: Daniel P. Berrangé <berrange(a)redhat.com> Cc: Dave Hansen <dave.hansen(a)linux.intel.com> Cc: H. Peter Anvin <hpa(a)zytor.com> Cc: Ingo Molnar <mingo(a)redhat.com> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: stable(a)vger.kernel.org Reviewed-by: Elena Reshetova <elena.reshetova(a)intel.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov(a)linux.intel.com> Reviewed-by: Theodore Ts'o <tytso(a)mit.edu> Signed-off-by: Jason A. Donenfeld <Jason(a)zx2c4.com> --- Changes v3->v4: - Add stable@ tag and reviewed-by lines. - Add comment for Dave explaining where the "32" comes from. arch/x86/coco/core.c | 40 +++++++++++++++++++++++++++++++++++++ arch/x86/include/asm/coco.h | 2 ++ arch/x86/kernel/setup.c | 2 ++ 3 files changed, 44 insertions(+) diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c index eeec9986570e..0e988bff4aec 100644 --- a/arch/x86/coco/core.c +++ b/arch/x86/coco/core.c @@ -3,13 +3,16 @@ * Confidential Computing Platform Capability checks * * Copyright (C) 2021 Advanced Micro Devices, Inc. + * Copyright (C) 2024 Jason A. Donenfeld <Jason(a)zx2c4.com>. All Rights Reserved. * * Author: Tom Lendacky <thomas.lendacky(a)amd.com> */ #include <linux/export.h> #include <linux/cc_platform.h> +#include <linux/random.h> +#include <asm/archrandom.h> #include <asm/coco.h> #include <asm/processor.h> @@ -153,3 +156,40 @@ __init void cc_set_mask(u64 mask) { cc_mask = mask; } + +__init void cc_random_init(void) +{ + /* + * The seed is 32 bytes (in units of longs), which is 256 bits, which + * is the security level that the RNG is targeting. + */ + unsigned long rng_seed[32 / sizeof(long)]; + size_t i, longs; + + if (cc_vendor == CC_VENDOR_NONE) + return; + + /* + * Since the CoCo threat model includes the host, the only reliable + * source of entropy that can be neither observed nor manipulated is + * RDRAND. Usually, RDRAND failure is considered tolerable, but since + * CoCo guests have no other unobservable source of entropy, it's + * important to at least ensure the RNG gets some initial random seeds. + */ + for (i = 0; i < ARRAY_SIZE(rng_seed); i += longs) { + longs = arch_get_random_longs(&rng_seed[i], ARRAY_SIZE(rng_seed) - i); + + /* + * A zero return value means that the guest doesn't have RDRAND + * or the CPU is physically broken, and in both cases that + * means most crypto inside of the CoCo instance will be + * broken, defeating the purpose of CoCo in the first place. So + * just panic here because it's absolutely unsafe to continue + * executing. + */ + if (longs == 0) + panic("RDRAND is defective."); + } + add_device_randomness(rng_seed, sizeof(rng_seed)); + memzero_explicit(rng_seed, sizeof(rng_seed)); +} diff --git a/arch/x86/include/asm/coco.h b/arch/x86/include/asm/coco.h index 76c310b19b11..e9d059449885 100644 --- a/arch/x86/include/asm/coco.h +++ b/arch/x86/include/asm/coco.h @@ -15,6 +15,7 @@ extern enum cc_vendor cc_vendor; void cc_set_mask(u64 mask); u64 cc_mkenc(u64 val); u64 cc_mkdec(u64 val); +void cc_random_init(void); #else #define cc_vendor (CC_VENDOR_NONE) @@ -27,6 +28,7 @@ static inline u64 cc_mkdec(u64 val) { return val; } +static inline void cc_random_init(void) { } #endif #endif /* _ASM_X86_COCO_H */ diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 84201071dfac..30a653cfc7d2 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -36,6 +36,7 @@ #include <asm/bios_ebda.h> #include <asm/bugs.h> #include <asm/cacheinfo.h> +#include <asm/coco.h> #include <asm/cpu.h> #include <asm/efi.h> #include <asm/gart.h> @@ -994,6 +995,7 @@ void __init setup_arch(char **cmdline_p) * memory size. */ mem_encrypt_setup_arch(); + cc_random_init(); efi_fake_memmap(); efi_find_mirror(); -- 2.43.2

11 months

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[PATCH] arm64/ptrace: Use saved floating point state type to determine SVE layout

by Mark Brown

The SVE register sets have two different formats, one of which is a wrapped version of the standard FPSIMD register set and another with actual SVE register data. At present we check TIF_SVE to see if full SVE register state should be provided when reading the SVE regset but if we were in a syscall we may have saved only floating point registers even though that is set. Fix this and simplify the logic by checking and using the format which we recorded when deciding if we should use FPSIMD or SVE format. Fixes: 8c845e273104 ("arm64/sve: Leave SVE enabled on syscall if we don't context switch") Signed-off-by: Mark Brown <broonie(a)kernel.org> Cc: stable(a)vger.kernel.org --- arch/arm64/kernel/ptrace.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 162b030ab9da..0d022599eb61 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -761,7 +761,6 @@ static void sve_init_header_from_task(struct user_sve_header *header, { unsigned int vq; bool active; - bool fpsimd_only; enum vec_type task_type; memset(header, 0, sizeof(*header)); @@ -777,12 +776,10 @@ static void sve_init_header_from_task(struct user_sve_header *header, case ARM64_VEC_SVE: if (test_tsk_thread_flag(target, TIF_SVE_VL_INHERIT)) header->flags |= SVE_PT_VL_INHERIT; - fpsimd_only = !test_tsk_thread_flag(target, TIF_SVE); break; case ARM64_VEC_SME: if (test_tsk_thread_flag(target, TIF_SME_VL_INHERIT)) header->flags |= SVE_PT_VL_INHERIT; - fpsimd_only = false; break; default: WARN_ON_ONCE(1); @@ -790,7 +787,7 @@ static void sve_init_header_from_task(struct user_sve_header *header, } if (active) { - if (fpsimd_only) { + if (target->thread.fp_type == FP_STATE_FPSIMD) { header->flags |= SVE_PT_REGS_FPSIMD; } else { header->flags |= SVE_PT_REGS_SVE; --- base-commit: 4cece764965020c22cff7665b18a012006359095 change-id: 20240129-arm64-ptrace-fp-type-d3ce48f8883e Best regards, -- Mark Brown <broonie(a)kernel.org>

11 months

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[PATCH net v3] virtio_net: Do not send RSS key if it is not supported

by Breno Leitao

There is a bug when setting the RSS options in virtio_net that can break the whole machine, getting the kernel into an infinite loop. Running the following command in any QEMU virtual machine with virtionet will reproduce this problem: # ethtool -X eth0 hfunc toeplitz This is how the problem happens: 1) ethtool_set_rxfh() calls virtnet_set_rxfh() 2) virtnet_set_rxfh() calls virtnet_commit_rss_command() 3) virtnet_commit_rss_command() populates 4 entries for the rss scatter-gather 4) Since the command above does not have a key, then the last scatter-gatter entry will be zeroed, since rss_key_size == 0. sg_buf_size = vi->rss_key_size; 5) This buffer is passed to qemu, but qemu is not happy with a buffer with zero length, and do the following in virtqueue_map_desc() (QEMU function): if (!sz) { virtio_error(vdev, "virtio: zero sized buffers are not allowed"); 6) virtio_error() (also QEMU function) set the device as broken vdev->broken = true; 7) Qemu bails out, and do not repond this crazy kernel. 8) The kernel is waiting for the response to come back (function virtnet_send_command()) 9) The kernel is waiting doing the following : while (!virtqueue_get_buf(vi->cvq, &tmp) && !virtqueue_is_broken(vi->cvq)) cpu_relax(); 10) None of the following functions above is true, thus, the kernel loops here forever. Keeping in mind that virtqueue_is_broken() does not look at the qemu `vdev->broken`, so, it never realizes that the vitio is broken at QEMU side. Fix it by not sending RSS commands if the feature is not available in the device. Fixes: c7114b1249fa ("drivers/net/virtio_net: Added basic RSS support.") Cc: stable(a)vger.kernel.org Cc: qemu-devel(a)nongnu.org Signed-off-by: Breno Leitao <leitao(a)debian.org> --- Changelog: V2: * Moved from creating a valid packet, by rejecting the request completely V3: * Got some good feedback from and Xuan Zhuo and Heng Qi, and reworked the rejection path. --- drivers/net/virtio_net.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index c22d1118a133..c4a21ec51adf 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -3807,6 +3807,7 @@ static int virtnet_set_rxfh(struct net_device *dev, struct netlink_ext_ack *extack) { struct virtnet_info *vi = netdev_priv(dev); + bool update = false; int i; if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE && @@ -3814,13 +3815,24 @@ static int virtnet_set_rxfh(struct net_device *dev, return -EOPNOTSUPP; if (rxfh->indir) { + if (!vi->has_rss) + return -EOPNOTSUPP; + for (i = 0; i < vi->rss_indir_table_size; ++i) vi->ctrl->rss.indirection_table[i] = rxfh->indir[i]; + update = true; } - if (rxfh->key) + + if (rxfh->key) { + if (!vi->has_rss && !vi->has_rss_hash_report) + return -EOPNOTSUPP; + memcpy(vi->ctrl->rss.key, rxfh->key, vi->rss_key_size); + update = true; + } - virtnet_commit_rss_command(vi); + if (update) + virtnet_commit_rss_command(vi); return 0; } @@ -4729,13 +4741,15 @@ static int virtnet_probe(struct virtio_device *vdev) if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT)) vi->has_rss_hash_report = true; - if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS)) + if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS)) { vi->has_rss = true; - if (vi->has_rss || vi->has_rss_hash_report) { vi->rss_indir_table_size = virtio_cread16(vdev, offsetof(struct virtio_net_config, rss_max_indirection_table_length)); + } + + if (vi->has_rss || vi->has_rss_hash_report) { vi->rss_key_size = virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size)); -- 2.43.0

11 months

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[PATCH] drm/vkms: call drm_atomic_helper_shutdown before drm_dev_put()

by Guo Mengqi

commit 73a82b22963d ("drm/atomic: Fix potential use-after-free in nonblocking commits") introduced drm_dev_get/put() to drm_atomic_helper_shutdown(). And this cause problem in vkms driver exit process. vkms_exit() drm_dev_put() vkms_release() drm_atomic_helper_shutdown() drm_dev_get() drm_dev_put() vkms_release() ------ null pointer access Using 4.19 stable x86 image on qemu, below stacktrace can be triggered by load and unload vkms.ko. root:~ # insmod vkms.ko [ 142.135449] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013). [ 142.138713] [drm] Driver supports precise vblank timestamp query. [ 142.142390] [drm] Initialized vkms 1.0.0 20180514 for virtual device on minor 0 root:~ # rmmod vkms.ko [ 144.093710] BUG: unable to handle kernel NULL pointer dereference at 00000000000000a0 [ 144.097491] PGD 800000023624e067 P4D 800000023624e067 PUD 22ab59067 PMD 0 [ 144.100802] Oops: 0000 [#1] SMP PTI [ 144.102502] CPU: 0 PID: 3615 Comm: rmmod Not tainted 4.19.310 #1 [ 144.104452] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 144.107238] RIP: 0010:device_del+0x34/0x3a0 ... [ 144.131323] Call Trace: [ 144.131962] ? __die+0x7d/0xc0 [ 144.132711] ? no_context+0x152/0x3b0 [ 144.133605] ? wake_up_q+0x70/0x70 [ 144.134436] ? __do_page_fault+0x342/0x4b0 [ 144.135445] ? __switch_to_asm+0x41/0x70 [ 144.136416] ? __switch_to_asm+0x35/0x70 [ 144.137366] ? page_fault+0x1e/0x30 [ 144.138214] ? __drm_atomic_state_free+0x51/0x60 [ 144.139331] ? device_del+0x34/0x3a0 [ 144.140197] platform_device_del.part.14+0x19/0x70 [ 144.141348] platform_device_unregister+0xe/0x20 [ 144.142458] vkms_release+0x10/0x30 [vkms] [ 144.143449] __drm_atomic_helper_disable_all.constprop.31+0x13b/0x150 [ 144.144980] drm_atomic_helper_shutdown+0x4b/0x90 [ 144.146102] vkms_release+0x18/0x30 [vkms] [ 144.147107] vkms_exit+0x29/0x8ec [vkms] [ 144.148053] __x64_sys_delete_module+0x155/0x220 [ 144.149168] do_syscall_64+0x43/0x100 [ 144.150056] entry_SYSCALL_64_after_hwframe+0x5c/0xc1 It seems that the proper unload sequence is: drm_atomic_helper_shutdown(); drm_dev_put(); Just put drm_atomic_helper_shutdown() before drm_dev_put() should solve the problem. Fixes: 73a82b22963d ("drm/atomic: Fix potential use-after-free in nonblocking commits") Signed-off-by: Guo Mengqi <guomengqi3(a)huawei.com> --- drivers/gpu/drm/vkms/vkms_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c index b1201c18d3eb..d32e08f17427 100644 --- a/drivers/gpu/drm/vkms/vkms_drv.c +++ b/drivers/gpu/drm/vkms/vkms_drv.c @@ -39,7 +39,6 @@ static void vkms_release(struct drm_device *dev) struct vkms_device *vkms = container_of(dev, struct vkms_device, drm); platform_device_unregister(vkms->platform); - drm_atomic_helper_shutdown(&vkms->drm); drm_mode_config_cleanup(&vkms->drm); drm_dev_fini(&vkms->drm); } @@ -137,6 +136,7 @@ static void __exit vkms_exit(void) } drm_dev_unregister(&vkms_device->drm); + drm_atomic_helper_shutdown(&vkms_device->drm); drm_dev_put(&vkms_device->drm); kfree(vkms_device); -- 2.17.1

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