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FAILED: patch "[PATCH] mm/hugetlb: fix avoid_reserve to allow taking folio from" 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 58db7c5fbe7daa42098d4965133a864f98ba90ba # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025021036-joyride-vitality-e81d@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 58db7c5fbe7daa42098d4965133a864f98ba90ba Mon Sep 17 00:00:00 2001 From: Peter Xu <peterx(a)redhat.com> Date: Tue, 7 Jan 2025 15:39:56 -0500 Subject: [PATCH] mm/hugetlb: fix avoid_reserve to allow taking folio from subpool Patch series "mm/hugetlb: Refactor hugetlb allocation resv accounting", v2. This is a follow up on Ackerley's series here as replacement: https://lore.kernel.org/r/cover.1728684491.git.ackerleytng@google.com The goal of this series is to cleanup hugetlb resv accounting, especially during folio allocation, to decouple a few things: - Hugetlb folios v.s. Hugetlbfs: IOW, the hope is in the future hugetlb folios can be allocated completely without hugetlbfs. - Decouple VMA v.s. hugetlb folio allocations: allocating a hugetlb folio should not always require a hugetlbfs VMA. For example, either it got allocated from the inode level (see hugetlbfs_fallocate() where it used a pesudo VMA for allocation), or it can be allocated by other kernel subsystems. It paves way for other users to allocate hugetlb folios out of either system reservations, or subpools (instead of hugetlbfs, as a file system). For longer term, this prepares hugetlb as a separate concept versus hugetlbfs, so that hugetlb folios can be allocated by not only hugetlbfs and other things. Tests I've done: - I had a reproducer in patch 1 for the bug I found, this will start to work after patch 1 or the whole set applied. - Hugetlb regression tests (on x86_64 2MBs), includes: - All vmtests on hugetlbfs - libhugetlbfs test suite (which may fail some tests, but no new failures will be introduced by this series, so all such failures happen before this series so shouldn't be relevant). This patch (of 7): Since commit 04f2cbe35699 ("hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed"), avoid_reserve was introduced for a special case of CoW on hugetlb private mappings, and only if the owner VMA is trying to allocate yet another hugetlb folio that is not reserved within the private vma reserved map. Later on, in commit d85f69b0b533 ("mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate"), alloc_huge_page() enforced to not consume any global reservation as long as avoid_reserve=true. This operation doesn't look correct, because even if it will enforce the allocation to not use global reservation at all, it will still try to take one reservation from the spool (if the subpool existed). Then since the spool reserved pages take from global reservation, it'll also take one reservation globally. Logically it can cause global reservation to go wrong. I wrote a reproducer below, trigger this special path, and every run of such program will cause global reservation count to increment by one, until it hits the number of free pages: #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <stdio.h> #include <fcntl.h> #include <errno.h> #include <unistd.h> #include <stdlib.h> #include <sys/mman.h> #define MSIZE (2UL << 20) int main(int argc, char *argv[]) { const char *path; int *buf; int fd, ret; pid_t child; if (argc < 2) { printf("usage: %s <hugetlb_file>\n", argv[0]); return -1; } path = argv[1]; fd = open(path, O_RDWR | O_CREAT, 0666); if (fd < 0) { perror("open failed"); return -1; } ret = fallocate(fd, 0, 0, MSIZE); if (ret != 0) { perror("fallocate"); return -1; } buf = mmap(NULL, MSIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); if (buf == MAP_FAILED) { perror("mmap() failed"); return -1; } /* Allocate a page */ *buf = 1; child = fork(); if (child == 0) { /* child doesn't need to do anything */ exit(0); } /* Trigger CoW from owner */ *buf = 2; munmap(buf, MSIZE); close(fd); unlink(path); return 0; } It can only reproduce with a sub-mount when there're reserved pages on the spool, like: # sysctl vm.nr_hugepages=128 # mkdir ./hugetlb-pool # mount -t hugetlbfs -o min_size=8M,pagesize=2M none ./hugetlb-pool Then run the reproducer on the mountpoint: # ./reproducer ./hugetlb-pool/test Fix it by taking the reservation from spool if available. In general, avoid_reserve is IMHO more about "avoid vma resv map", not spool's. I copied stable, however I have no intention for backporting if it's not a clean cherry-pick, because private hugetlb mapping, and then fork() on top is too rare to hit. Link: https://lkml.kernel.org/r/20250107204002.2683356-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20250107204002.2683356-2-peterx@redhat.com Fixes: d85f69b0b533 ("mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate") Signed-off-by: Peter Xu <peterx(a)redhat.com> Reviewed-by: Ackerley Tng <ackerleytng(a)google.com> Tested-by: Ackerley Tng <ackerleytng(a)google.com> Reviewed-by: Oscar Salvador <osalvador(a)suse.de> Cc: Breno Leitao <leitao(a)debian.org> Cc: Muchun Song <muchun.song(a)linux.dev> Cc: Naoya Horiguchi <nao.horiguchi(a)gmail.com> Cc: Rik van Riel <riel(a)surriel.com> Cc: Roman Gushchin <roman.gushchin(a)linux.dev> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 312ed27b9721..a10d376cb1a8 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1398,8 +1398,7 @@ static unsigned long available_huge_pages(struct hstate *h) static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, struct vm_area_struct *vma, - unsigned long address, int avoid_reserve, - long chg) + unsigned long address, long chg) { struct folio *folio = NULL; struct mempolicy *mpol; @@ -1415,10 +1414,6 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, if (!vma_has_reserves(vma, chg) && !available_huge_pages(h)) goto err; - /* If reserves cannot be used, ensure enough pages are in the pool */ - if (avoid_reserve && !available_huge_pages(h)) - goto err; - gfp_mask = htlb_alloc_mask(h); nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask); @@ -1434,7 +1429,7 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask, nid, nodemask); - if (folio && !avoid_reserve && vma_has_reserves(vma, chg)) { + if (folio && vma_has_reserves(vma, chg)) { folio_set_hugetlb_restore_reserve(folio); h->resv_huge_pages--; } @@ -3051,17 +3046,6 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, gbl_chg = hugepage_subpool_get_pages(spool, 1); if (gbl_chg < 0) goto out_end_reservation; - - /* - * Even though there was no reservation in the region/reserve - * map, there could be reservations associated with the - * subpool that can be used. This would be indicated if the - * return value of hugepage_subpool_get_pages() is zero. - * However, if avoid_reserve is specified we still avoid even - * the subpool reservations. - */ - if (avoid_reserve) - gbl_chg = 1; } /* If this allocation is not consuming a reservation, charge it now. @@ -3084,7 +3068,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, * from the global free pool (global change). gbl_chg == 0 indicates * a reservation exists for the allocation. */ - folio = dequeue_hugetlb_folio_vma(h, vma, addr, avoid_reserve, gbl_chg); + folio = dequeue_hugetlb_folio_vma(h, vma, addr, gbl_chg); if (!folio) { spin_unlock_irq(&hugetlb_lock); folio = alloc_buddy_hugetlb_folio_with_mpol(h, vma, addr);

9 months, 1 week

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FAILED: patch "[PATCH] mm/hugetlb: fix avoid_reserve to allow taking folio from" 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 58db7c5fbe7daa42098d4965133a864f98ba90ba # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025021033-cupcake-spud-c04d@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 58db7c5fbe7daa42098d4965133a864f98ba90ba Mon Sep 17 00:00:00 2001 From: Peter Xu <peterx(a)redhat.com> Date: Tue, 7 Jan 2025 15:39:56 -0500 Subject: [PATCH] mm/hugetlb: fix avoid_reserve to allow taking folio from subpool Patch series "mm/hugetlb: Refactor hugetlb allocation resv accounting", v2. This is a follow up on Ackerley's series here as replacement: https://lore.kernel.org/r/cover.1728684491.git.ackerleytng@google.com The goal of this series is to cleanup hugetlb resv accounting, especially during folio allocation, to decouple a few things: - Hugetlb folios v.s. Hugetlbfs: IOW, the hope is in the future hugetlb folios can be allocated completely without hugetlbfs. - Decouple VMA v.s. hugetlb folio allocations: allocating a hugetlb folio should not always require a hugetlbfs VMA. For example, either it got allocated from the inode level (see hugetlbfs_fallocate() where it used a pesudo VMA for allocation), or it can be allocated by other kernel subsystems. It paves way for other users to allocate hugetlb folios out of either system reservations, or subpools (instead of hugetlbfs, as a file system). For longer term, this prepares hugetlb as a separate concept versus hugetlbfs, so that hugetlb folios can be allocated by not only hugetlbfs and other things. Tests I've done: - I had a reproducer in patch 1 for the bug I found, this will start to work after patch 1 or the whole set applied. - Hugetlb regression tests (on x86_64 2MBs), includes: - All vmtests on hugetlbfs - libhugetlbfs test suite (which may fail some tests, but no new failures will be introduced by this series, so all such failures happen before this series so shouldn't be relevant). This patch (of 7): Since commit 04f2cbe35699 ("hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed"), avoid_reserve was introduced for a special case of CoW on hugetlb private mappings, and only if the owner VMA is trying to allocate yet another hugetlb folio that is not reserved within the private vma reserved map. Later on, in commit d85f69b0b533 ("mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate"), alloc_huge_page() enforced to not consume any global reservation as long as avoid_reserve=true. This operation doesn't look correct, because even if it will enforce the allocation to not use global reservation at all, it will still try to take one reservation from the spool (if the subpool existed). Then since the spool reserved pages take from global reservation, it'll also take one reservation globally. Logically it can cause global reservation to go wrong. I wrote a reproducer below, trigger this special path, and every run of such program will cause global reservation count to increment by one, until it hits the number of free pages: #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <stdio.h> #include <fcntl.h> #include <errno.h> #include <unistd.h> #include <stdlib.h> #include <sys/mman.h> #define MSIZE (2UL << 20) int main(int argc, char *argv[]) { const char *path; int *buf; int fd, ret; pid_t child; if (argc < 2) { printf("usage: %s <hugetlb_file>\n", argv[0]); return -1; } path = argv[1]; fd = open(path, O_RDWR | O_CREAT, 0666); if (fd < 0) { perror("open failed"); return -1; } ret = fallocate(fd, 0, 0, MSIZE); if (ret != 0) { perror("fallocate"); return -1; } buf = mmap(NULL, MSIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); if (buf == MAP_FAILED) { perror("mmap() failed"); return -1; } /* Allocate a page */ *buf = 1; child = fork(); if (child == 0) { /* child doesn't need to do anything */ exit(0); } /* Trigger CoW from owner */ *buf = 2; munmap(buf, MSIZE); close(fd); unlink(path); return 0; } It can only reproduce with a sub-mount when there're reserved pages on the spool, like: # sysctl vm.nr_hugepages=128 # mkdir ./hugetlb-pool # mount -t hugetlbfs -o min_size=8M,pagesize=2M none ./hugetlb-pool Then run the reproducer on the mountpoint: # ./reproducer ./hugetlb-pool/test Fix it by taking the reservation from spool if available. In general, avoid_reserve is IMHO more about "avoid vma resv map", not spool's. I copied stable, however I have no intention for backporting if it's not a clean cherry-pick, because private hugetlb mapping, and then fork() on top is too rare to hit. Link: https://lkml.kernel.org/r/20250107204002.2683356-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20250107204002.2683356-2-peterx@redhat.com Fixes: d85f69b0b533 ("mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate") Signed-off-by: Peter Xu <peterx(a)redhat.com> Reviewed-by: Ackerley Tng <ackerleytng(a)google.com> Tested-by: Ackerley Tng <ackerleytng(a)google.com> Reviewed-by: Oscar Salvador <osalvador(a)suse.de> Cc: Breno Leitao <leitao(a)debian.org> Cc: Muchun Song <muchun.song(a)linux.dev> Cc: Naoya Horiguchi <nao.horiguchi(a)gmail.com> Cc: Rik van Riel <riel(a)surriel.com> Cc: Roman Gushchin <roman.gushchin(a)linux.dev> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 312ed27b9721..a10d376cb1a8 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1398,8 +1398,7 @@ static unsigned long available_huge_pages(struct hstate *h) static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, struct vm_area_struct *vma, - unsigned long address, int avoid_reserve, - long chg) + unsigned long address, long chg) { struct folio *folio = NULL; struct mempolicy *mpol; @@ -1415,10 +1414,6 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, if (!vma_has_reserves(vma, chg) && !available_huge_pages(h)) goto err; - /* If reserves cannot be used, ensure enough pages are in the pool */ - if (avoid_reserve && !available_huge_pages(h)) - goto err; - gfp_mask = htlb_alloc_mask(h); nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask); @@ -1434,7 +1429,7 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask, nid, nodemask); - if (folio && !avoid_reserve && vma_has_reserves(vma, chg)) { + if (folio && vma_has_reserves(vma, chg)) { folio_set_hugetlb_restore_reserve(folio); h->resv_huge_pages--; } @@ -3051,17 +3046,6 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, gbl_chg = hugepage_subpool_get_pages(spool, 1); if (gbl_chg < 0) goto out_end_reservation; - - /* - * Even though there was no reservation in the region/reserve - * map, there could be reservations associated with the - * subpool that can be used. This would be indicated if the - * return value of hugepage_subpool_get_pages() is zero. - * However, if avoid_reserve is specified we still avoid even - * the subpool reservations. - */ - if (avoid_reserve) - gbl_chg = 1; } /* If this allocation is not consuming a reservation, charge it now. @@ -3084,7 +3068,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, * from the global free pool (global change). gbl_chg == 0 indicates * a reservation exists for the allocation. */ - folio = dequeue_hugetlb_folio_vma(h, vma, addr, avoid_reserve, gbl_chg); + folio = dequeue_hugetlb_folio_vma(h, vma, addr, gbl_chg); if (!folio) { spin_unlock_irq(&hugetlb_lock); folio = alloc_buddy_hugetlb_folio_with_mpol(h, vma, addr);

9 months, 1 week

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FAILED: patch "[PATCH] mm/hugetlb: fix avoid_reserve to allow taking folio from" 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 58db7c5fbe7daa42098d4965133a864f98ba90ba # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025021025-deflector-judge-df07@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 58db7c5fbe7daa42098d4965133a864f98ba90ba Mon Sep 17 00:00:00 2001 From: Peter Xu <peterx(a)redhat.com> Date: Tue, 7 Jan 2025 15:39:56 -0500 Subject: [PATCH] mm/hugetlb: fix avoid_reserve to allow taking folio from subpool Patch series "mm/hugetlb: Refactor hugetlb allocation resv accounting", v2. This is a follow up on Ackerley's series here as replacement: https://lore.kernel.org/r/cover.1728684491.git.ackerleytng@google.com The goal of this series is to cleanup hugetlb resv accounting, especially during folio allocation, to decouple a few things: - Hugetlb folios v.s. Hugetlbfs: IOW, the hope is in the future hugetlb folios can be allocated completely without hugetlbfs. - Decouple VMA v.s. hugetlb folio allocations: allocating a hugetlb folio should not always require a hugetlbfs VMA. For example, either it got allocated from the inode level (see hugetlbfs_fallocate() where it used a pesudo VMA for allocation), or it can be allocated by other kernel subsystems. It paves way for other users to allocate hugetlb folios out of either system reservations, or subpools (instead of hugetlbfs, as a file system). For longer term, this prepares hugetlb as a separate concept versus hugetlbfs, so that hugetlb folios can be allocated by not only hugetlbfs and other things. Tests I've done: - I had a reproducer in patch 1 for the bug I found, this will start to work after patch 1 or the whole set applied. - Hugetlb regression tests (on x86_64 2MBs), includes: - All vmtests on hugetlbfs - libhugetlbfs test suite (which may fail some tests, but no new failures will be introduced by this series, so all such failures happen before this series so shouldn't be relevant). This patch (of 7): Since commit 04f2cbe35699 ("hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed"), avoid_reserve was introduced for a special case of CoW on hugetlb private mappings, and only if the owner VMA is trying to allocate yet another hugetlb folio that is not reserved within the private vma reserved map. Later on, in commit d85f69b0b533 ("mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate"), alloc_huge_page() enforced to not consume any global reservation as long as avoid_reserve=true. This operation doesn't look correct, because even if it will enforce the allocation to not use global reservation at all, it will still try to take one reservation from the spool (if the subpool existed). Then since the spool reserved pages take from global reservation, it'll also take one reservation globally. Logically it can cause global reservation to go wrong. I wrote a reproducer below, trigger this special path, and every run of such program will cause global reservation count to increment by one, until it hits the number of free pages: #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <stdio.h> #include <fcntl.h> #include <errno.h> #include <unistd.h> #include <stdlib.h> #include <sys/mman.h> #define MSIZE (2UL << 20) int main(int argc, char *argv[]) { const char *path; int *buf; int fd, ret; pid_t child; if (argc < 2) { printf("usage: %s <hugetlb_file>\n", argv[0]); return -1; } path = argv[1]; fd = open(path, O_RDWR | O_CREAT, 0666); if (fd < 0) { perror("open failed"); return -1; } ret = fallocate(fd, 0, 0, MSIZE); if (ret != 0) { perror("fallocate"); return -1; } buf = mmap(NULL, MSIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); if (buf == MAP_FAILED) { perror("mmap() failed"); return -1; } /* Allocate a page */ *buf = 1; child = fork(); if (child == 0) { /* child doesn't need to do anything */ exit(0); } /* Trigger CoW from owner */ *buf = 2; munmap(buf, MSIZE); close(fd); unlink(path); return 0; } It can only reproduce with a sub-mount when there're reserved pages on the spool, like: # sysctl vm.nr_hugepages=128 # mkdir ./hugetlb-pool # mount -t hugetlbfs -o min_size=8M,pagesize=2M none ./hugetlb-pool Then run the reproducer on the mountpoint: # ./reproducer ./hugetlb-pool/test Fix it by taking the reservation from spool if available. In general, avoid_reserve is IMHO more about "avoid vma resv map", not spool's. I copied stable, however I have no intention for backporting if it's not a clean cherry-pick, because private hugetlb mapping, and then fork() on top is too rare to hit. Link: https://lkml.kernel.org/r/20250107204002.2683356-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20250107204002.2683356-2-peterx@redhat.com Fixes: d85f69b0b533 ("mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate") Signed-off-by: Peter Xu <peterx(a)redhat.com> Reviewed-by: Ackerley Tng <ackerleytng(a)google.com> Tested-by: Ackerley Tng <ackerleytng(a)google.com> Reviewed-by: Oscar Salvador <osalvador(a)suse.de> Cc: Breno Leitao <leitao(a)debian.org> Cc: Muchun Song <muchun.song(a)linux.dev> Cc: Naoya Horiguchi <nao.horiguchi(a)gmail.com> Cc: Rik van Riel <riel(a)surriel.com> Cc: Roman Gushchin <roman.gushchin(a)linux.dev> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 312ed27b9721..a10d376cb1a8 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1398,8 +1398,7 @@ static unsigned long available_huge_pages(struct hstate *h) static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, struct vm_area_struct *vma, - unsigned long address, int avoid_reserve, - long chg) + unsigned long address, long chg) { struct folio *folio = NULL; struct mempolicy *mpol; @@ -1415,10 +1414,6 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, if (!vma_has_reserves(vma, chg) && !available_huge_pages(h)) goto err; - /* If reserves cannot be used, ensure enough pages are in the pool */ - if (avoid_reserve && !available_huge_pages(h)) - goto err; - gfp_mask = htlb_alloc_mask(h); nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask); @@ -1434,7 +1429,7 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask, nid, nodemask); - if (folio && !avoid_reserve && vma_has_reserves(vma, chg)) { + if (folio && vma_has_reserves(vma, chg)) { folio_set_hugetlb_restore_reserve(folio); h->resv_huge_pages--; } @@ -3051,17 +3046,6 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, gbl_chg = hugepage_subpool_get_pages(spool, 1); if (gbl_chg < 0) goto out_end_reservation; - - /* - * Even though there was no reservation in the region/reserve - * map, there could be reservations associated with the - * subpool that can be used. This would be indicated if the - * return value of hugepage_subpool_get_pages() is zero. - * However, if avoid_reserve is specified we still avoid even - * the subpool reservations. - */ - if (avoid_reserve) - gbl_chg = 1; } /* If this allocation is not consuming a reservation, charge it now. @@ -3084,7 +3068,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, * from the global free pool (global change). gbl_chg == 0 indicates * a reservation exists for the allocation. */ - folio = dequeue_hugetlb_folio_vma(h, vma, addr, avoid_reserve, gbl_chg); + folio = dequeue_hugetlb_folio_vma(h, vma, addr, gbl_chg); if (!folio) { spin_unlock_irq(&hugetlb_lock); folio = alloc_buddy_hugetlb_folio_with_mpol(h, vma, addr);

9 months, 1 week

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FAILED: patch "[PATCH] mm/hugetlb: fix avoid_reserve to allow taking folio from" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-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-6.1.y git checkout FETCH_HEAD git cherry-pick -x 58db7c5fbe7daa42098d4965133a864f98ba90ba # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025021023-plank-tribesman-b3f2@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 58db7c5fbe7daa42098d4965133a864f98ba90ba Mon Sep 17 00:00:00 2001 From: Peter Xu <peterx(a)redhat.com> Date: Tue, 7 Jan 2025 15:39:56 -0500 Subject: [PATCH] mm/hugetlb: fix avoid_reserve to allow taking folio from subpool Patch series "mm/hugetlb: Refactor hugetlb allocation resv accounting", v2. This is a follow up on Ackerley's series here as replacement: https://lore.kernel.org/r/cover.1728684491.git.ackerleytng@google.com The goal of this series is to cleanup hugetlb resv accounting, especially during folio allocation, to decouple a few things: - Hugetlb folios v.s. Hugetlbfs: IOW, the hope is in the future hugetlb folios can be allocated completely without hugetlbfs. - Decouple VMA v.s. hugetlb folio allocations: allocating a hugetlb folio should not always require a hugetlbfs VMA. For example, either it got allocated from the inode level (see hugetlbfs_fallocate() where it used a pesudo VMA for allocation), or it can be allocated by other kernel subsystems. It paves way for other users to allocate hugetlb folios out of either system reservations, or subpools (instead of hugetlbfs, as a file system). For longer term, this prepares hugetlb as a separate concept versus hugetlbfs, so that hugetlb folios can be allocated by not only hugetlbfs and other things. Tests I've done: - I had a reproducer in patch 1 for the bug I found, this will start to work after patch 1 or the whole set applied. - Hugetlb regression tests (on x86_64 2MBs), includes: - All vmtests on hugetlbfs - libhugetlbfs test suite (which may fail some tests, but no new failures will be introduced by this series, so all such failures happen before this series so shouldn't be relevant). This patch (of 7): Since commit 04f2cbe35699 ("hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed"), avoid_reserve was introduced for a special case of CoW on hugetlb private mappings, and only if the owner VMA is trying to allocate yet another hugetlb folio that is not reserved within the private vma reserved map. Later on, in commit d85f69b0b533 ("mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate"), alloc_huge_page() enforced to not consume any global reservation as long as avoid_reserve=true. This operation doesn't look correct, because even if it will enforce the allocation to not use global reservation at all, it will still try to take one reservation from the spool (if the subpool existed). Then since the spool reserved pages take from global reservation, it'll also take one reservation globally. Logically it can cause global reservation to go wrong. I wrote a reproducer below, trigger this special path, and every run of such program will cause global reservation count to increment by one, until it hits the number of free pages: #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <stdio.h> #include <fcntl.h> #include <errno.h> #include <unistd.h> #include <stdlib.h> #include <sys/mman.h> #define MSIZE (2UL << 20) int main(int argc, char *argv[]) { const char *path; int *buf; int fd, ret; pid_t child; if (argc < 2) { printf("usage: %s <hugetlb_file>\n", argv[0]); return -1; } path = argv[1]; fd = open(path, O_RDWR | O_CREAT, 0666); if (fd < 0) { perror("open failed"); return -1; } ret = fallocate(fd, 0, 0, MSIZE); if (ret != 0) { perror("fallocate"); return -1; } buf = mmap(NULL, MSIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); if (buf == MAP_FAILED) { perror("mmap() failed"); return -1; } /* Allocate a page */ *buf = 1; child = fork(); if (child == 0) { /* child doesn't need to do anything */ exit(0); } /* Trigger CoW from owner */ *buf = 2; munmap(buf, MSIZE); close(fd); unlink(path); return 0; } It can only reproduce with a sub-mount when there're reserved pages on the spool, like: # sysctl vm.nr_hugepages=128 # mkdir ./hugetlb-pool # mount -t hugetlbfs -o min_size=8M,pagesize=2M none ./hugetlb-pool Then run the reproducer on the mountpoint: # ./reproducer ./hugetlb-pool/test Fix it by taking the reservation from spool if available. In general, avoid_reserve is IMHO more about "avoid vma resv map", not spool's. I copied stable, however I have no intention for backporting if it's not a clean cherry-pick, because private hugetlb mapping, and then fork() on top is too rare to hit. Link: https://lkml.kernel.org/r/20250107204002.2683356-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20250107204002.2683356-2-peterx@redhat.com Fixes: d85f69b0b533 ("mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate") Signed-off-by: Peter Xu <peterx(a)redhat.com> Reviewed-by: Ackerley Tng <ackerleytng(a)google.com> Tested-by: Ackerley Tng <ackerleytng(a)google.com> Reviewed-by: Oscar Salvador <osalvador(a)suse.de> Cc: Breno Leitao <leitao(a)debian.org> Cc: Muchun Song <muchun.song(a)linux.dev> Cc: Naoya Horiguchi <nao.horiguchi(a)gmail.com> Cc: Rik van Riel <riel(a)surriel.com> Cc: Roman Gushchin <roman.gushchin(a)linux.dev> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 312ed27b9721..a10d376cb1a8 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1398,8 +1398,7 @@ static unsigned long available_huge_pages(struct hstate *h) static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, struct vm_area_struct *vma, - unsigned long address, int avoid_reserve, - long chg) + unsigned long address, long chg) { struct folio *folio = NULL; struct mempolicy *mpol; @@ -1415,10 +1414,6 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, if (!vma_has_reserves(vma, chg) && !available_huge_pages(h)) goto err; - /* If reserves cannot be used, ensure enough pages are in the pool */ - if (avoid_reserve && !available_huge_pages(h)) - goto err; - gfp_mask = htlb_alloc_mask(h); nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask); @@ -1434,7 +1429,7 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask, nid, nodemask); - if (folio && !avoid_reserve && vma_has_reserves(vma, chg)) { + if (folio && vma_has_reserves(vma, chg)) { folio_set_hugetlb_restore_reserve(folio); h->resv_huge_pages--; } @@ -3051,17 +3046,6 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, gbl_chg = hugepage_subpool_get_pages(spool, 1); if (gbl_chg < 0) goto out_end_reservation; - - /* - * Even though there was no reservation in the region/reserve - * map, there could be reservations associated with the - * subpool that can be used. This would be indicated if the - * return value of hugepage_subpool_get_pages() is zero. - * However, if avoid_reserve is specified we still avoid even - * the subpool reservations. - */ - if (avoid_reserve) - gbl_chg = 1; } /* If this allocation is not consuming a reservation, charge it now. @@ -3084,7 +3068,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, * from the global free pool (global change). gbl_chg == 0 indicates * a reservation exists for the allocation. */ - folio = dequeue_hugetlb_folio_vma(h, vma, addr, avoid_reserve, gbl_chg); + folio = dequeue_hugetlb_folio_vma(h, vma, addr, gbl_chg); if (!folio) { spin_unlock_irq(&hugetlb_lock); folio = alloc_buddy_hugetlb_folio_with_mpol(h, vma, addr);

9 months, 1 week

1
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FAILED: patch "[PATCH] mm/hugetlb: fix avoid_reserve to allow taking folio from" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-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-6.6.y git checkout FETCH_HEAD git cherry-pick -x 58db7c5fbe7daa42098d4965133a864f98ba90ba # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025021020-copper-visibly-e6a9@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 58db7c5fbe7daa42098d4965133a864f98ba90ba Mon Sep 17 00:00:00 2001 From: Peter Xu <peterx(a)redhat.com> Date: Tue, 7 Jan 2025 15:39:56 -0500 Subject: [PATCH] mm/hugetlb: fix avoid_reserve to allow taking folio from subpool Patch series "mm/hugetlb: Refactor hugetlb allocation resv accounting", v2. This is a follow up on Ackerley's series here as replacement: https://lore.kernel.org/r/cover.1728684491.git.ackerleytng@google.com The goal of this series is to cleanup hugetlb resv accounting, especially during folio allocation, to decouple a few things: - Hugetlb folios v.s. Hugetlbfs: IOW, the hope is in the future hugetlb folios can be allocated completely without hugetlbfs. - Decouple VMA v.s. hugetlb folio allocations: allocating a hugetlb folio should not always require a hugetlbfs VMA. For example, either it got allocated from the inode level (see hugetlbfs_fallocate() where it used a pesudo VMA for allocation), or it can be allocated by other kernel subsystems. It paves way for other users to allocate hugetlb folios out of either system reservations, or subpools (instead of hugetlbfs, as a file system). For longer term, this prepares hugetlb as a separate concept versus hugetlbfs, so that hugetlb folios can be allocated by not only hugetlbfs and other things. Tests I've done: - I had a reproducer in patch 1 for the bug I found, this will start to work after patch 1 or the whole set applied. - Hugetlb regression tests (on x86_64 2MBs), includes: - All vmtests on hugetlbfs - libhugetlbfs test suite (which may fail some tests, but no new failures will be introduced by this series, so all such failures happen before this series so shouldn't be relevant). This patch (of 7): Since commit 04f2cbe35699 ("hugetlb: guarantee that COW faults for a process that called mmap(MAP_PRIVATE) on hugetlbfs will succeed"), avoid_reserve was introduced for a special case of CoW on hugetlb private mappings, and only if the owner VMA is trying to allocate yet another hugetlb folio that is not reserved within the private vma reserved map. Later on, in commit d85f69b0b533 ("mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate"), alloc_huge_page() enforced to not consume any global reservation as long as avoid_reserve=true. This operation doesn't look correct, because even if it will enforce the allocation to not use global reservation at all, it will still try to take one reservation from the spool (if the subpool existed). Then since the spool reserved pages take from global reservation, it'll also take one reservation globally. Logically it can cause global reservation to go wrong. I wrote a reproducer below, trigger this special path, and every run of such program will cause global reservation count to increment by one, until it hits the number of free pages: #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <stdio.h> #include <fcntl.h> #include <errno.h> #include <unistd.h> #include <stdlib.h> #include <sys/mman.h> #define MSIZE (2UL << 20) int main(int argc, char *argv[]) { const char *path; int *buf; int fd, ret; pid_t child; if (argc < 2) { printf("usage: %s <hugetlb_file>\n", argv[0]); return -1; } path = argv[1]; fd = open(path, O_RDWR | O_CREAT, 0666); if (fd < 0) { perror("open failed"); return -1; } ret = fallocate(fd, 0, 0, MSIZE); if (ret != 0) { perror("fallocate"); return -1; } buf = mmap(NULL, MSIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); if (buf == MAP_FAILED) { perror("mmap() failed"); return -1; } /* Allocate a page */ *buf = 1; child = fork(); if (child == 0) { /* child doesn't need to do anything */ exit(0); } /* Trigger CoW from owner */ *buf = 2; munmap(buf, MSIZE); close(fd); unlink(path); return 0; } It can only reproduce with a sub-mount when there're reserved pages on the spool, like: # sysctl vm.nr_hugepages=128 # mkdir ./hugetlb-pool # mount -t hugetlbfs -o min_size=8M,pagesize=2M none ./hugetlb-pool Then run the reproducer on the mountpoint: # ./reproducer ./hugetlb-pool/test Fix it by taking the reservation from spool if available. In general, avoid_reserve is IMHO more about "avoid vma resv map", not spool's. I copied stable, however I have no intention for backporting if it's not a clean cherry-pick, because private hugetlb mapping, and then fork() on top is too rare to hit. Link: https://lkml.kernel.org/r/20250107204002.2683356-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20250107204002.2683356-2-peterx@redhat.com Fixes: d85f69b0b533 ("mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate") Signed-off-by: Peter Xu <peterx(a)redhat.com> Reviewed-by: Ackerley Tng <ackerleytng(a)google.com> Tested-by: Ackerley Tng <ackerleytng(a)google.com> Reviewed-by: Oscar Salvador <osalvador(a)suse.de> Cc: Breno Leitao <leitao(a)debian.org> Cc: Muchun Song <muchun.song(a)linux.dev> Cc: Naoya Horiguchi <nao.horiguchi(a)gmail.com> Cc: Rik van Riel <riel(a)surriel.com> Cc: Roman Gushchin <roman.gushchin(a)linux.dev> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 312ed27b9721..a10d376cb1a8 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1398,8 +1398,7 @@ static unsigned long available_huge_pages(struct hstate *h) static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, struct vm_area_struct *vma, - unsigned long address, int avoid_reserve, - long chg) + unsigned long address, long chg) { struct folio *folio = NULL; struct mempolicy *mpol; @@ -1415,10 +1414,6 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, if (!vma_has_reserves(vma, chg) && !available_huge_pages(h)) goto err; - /* If reserves cannot be used, ensure enough pages are in the pool */ - if (avoid_reserve && !available_huge_pages(h)) - goto err; - gfp_mask = htlb_alloc_mask(h); nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask); @@ -1434,7 +1429,7 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h, folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask, nid, nodemask); - if (folio && !avoid_reserve && vma_has_reserves(vma, chg)) { + if (folio && vma_has_reserves(vma, chg)) { folio_set_hugetlb_restore_reserve(folio); h->resv_huge_pages--; } @@ -3051,17 +3046,6 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, gbl_chg = hugepage_subpool_get_pages(spool, 1); if (gbl_chg < 0) goto out_end_reservation; - - /* - * Even though there was no reservation in the region/reserve - * map, there could be reservations associated with the - * subpool that can be used. This would be indicated if the - * return value of hugepage_subpool_get_pages() is zero. - * However, if avoid_reserve is specified we still avoid even - * the subpool reservations. - */ - if (avoid_reserve) - gbl_chg = 1; } /* If this allocation is not consuming a reservation, charge it now. @@ -3084,7 +3068,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, * from the global free pool (global change). gbl_chg == 0 indicates * a reservation exists for the allocation. */ - folio = dequeue_hugetlb_folio_vma(h, vma, addr, avoid_reserve, gbl_chg); + folio = dequeue_hugetlb_folio_vma(h, vma, addr, gbl_chg); if (!folio) { spin_unlock_irq(&hugetlb_lock); folio = alloc_buddy_hugetlb_folio_with_mpol(h, vma, addr);

9 months, 1 week

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FAILED: patch "[PATCH] kfence: skip __GFP_THISNODE allocations on NUMA systems" 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 e64f81946adf68cd75e2207dd9a51668348a4af8 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025021058-paramount-dance-41da@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From e64f81946adf68cd75e2207dd9a51668348a4af8 Mon Sep 17 00:00:00 2001 From: Marco Elver <elver(a)google.com> Date: Fri, 24 Jan 2025 13:01:38 +0100 Subject: [PATCH] kfence: skip __GFP_THISNODE allocations on NUMA systems On NUMA systems, __GFP_THISNODE indicates that an allocation _must_ be on a particular node, and failure to allocate on the desired node will result in a failed allocation. Skip __GFP_THISNODE allocations if we are running on a NUMA system, since KFENCE can't guarantee which node its pool pages are allocated on. Link: https://lkml.kernel.org/r/20250124120145.410066-1-elver@google.com Fixes: 236e9f153852 ("kfence: skip all GFP_ZONEMASK allocations") Signed-off-by: Marco Elver <elver(a)google.com> Reported-by: Vlastimil Babka <vbabka(a)suse.cz> Acked-by: Vlastimil Babka <vbabka(a)suse.cz> Cc: Christoph Lameter <cl(a)linux.com> Cc: Alexander Potapenko <glider(a)google.com> Cc: Chistoph Lameter <cl(a)linux.com> Cc: Dmitriy Vyukov <dvyukov(a)google.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 67fc321db79b..102048821c22 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -21,6 +21,7 @@ #include <linux/log2.h> #include <linux/memblock.h> #include <linux/moduleparam.h> +#include <linux/nodemask.h> #include <linux/notifier.h> #include <linux/panic_notifier.h> #include <linux/random.h> @@ -1084,6 +1085,7 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) * properties (e.g. reside in DMAable memory). */ if ((flags & GFP_ZONEMASK) || + ((flags & __GFP_THISNODE) && num_online_nodes() > 1) || (s->flags & (SLAB_CACHE_DMA | SLAB_CACHE_DMA32))) { atomic_long_inc(&counters[KFENCE_COUNTER_SKIP_INCOMPAT]); return NULL;

9 months, 1 week

1
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FAILED: patch "[PATCH] xfs: Add error handling for xfs_reflink_cancel_cow_range" 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 26b63bee2f6e711c5a169997fd126fddcfb90848 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025021019-constrain-diligent-85b6@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 26b63bee2f6e711c5a169997fd126fddcfb90848 Mon Sep 17 00:00:00 2001 From: Wentao Liang <vulab(a)iscas.ac.cn> Date: Fri, 24 Jan 2025 11:45:09 +0800 Subject: [PATCH] xfs: Add error handling for xfs_reflink_cancel_cow_range In xfs_inactive(), xfs_reflink_cancel_cow_range() is called without error handling, risking unnoticed failures and inconsistent behavior compared to other parts of the code. Fix this issue by adding an error handling for the xfs_reflink_cancel_cow_range(), improving code robustness. Fixes: 6231848c3aa5 ("xfs: check for cow blocks before trying to clear them") Cc: stable(a)vger.kernel.org # v4.17 Reviewed-by: Darrick J. Wong <djwong(a)kernel.org> Signed-off-by: Wentao Liang <vulab(a)iscas.ac.cn> Signed-off-by: Carlos Maiolino <cem(a)kernel.org> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index c95fe1b1de4e..b1f9f156ec88 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -1404,8 +1404,11 @@ xfs_inactive( goto out; /* Try to clean out the cow blocks if there are any. */ - if (xfs_inode_has_cow_data(ip)) - xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, true); + if (xfs_inode_has_cow_data(ip)) { + error = xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, true); + if (error) + goto out; + } if (VFS_I(ip)->i_nlink != 0) { /*

9 months, 1 week

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FAILED: patch "[PATCH] xfs: Add error handling for xfs_reflink_cancel_cow_range" 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 26b63bee2f6e711c5a169997fd126fddcfb90848 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025021014-dedicate-recycled-1738@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 26b63bee2f6e711c5a169997fd126fddcfb90848 Mon Sep 17 00:00:00 2001 From: Wentao Liang <vulab(a)iscas.ac.cn> Date: Fri, 24 Jan 2025 11:45:09 +0800 Subject: [PATCH] xfs: Add error handling for xfs_reflink_cancel_cow_range In xfs_inactive(), xfs_reflink_cancel_cow_range() is called without error handling, risking unnoticed failures and inconsistent behavior compared to other parts of the code. Fix this issue by adding an error handling for the xfs_reflink_cancel_cow_range(), improving code robustness. Fixes: 6231848c3aa5 ("xfs: check for cow blocks before trying to clear them") Cc: stable(a)vger.kernel.org # v4.17 Reviewed-by: Darrick J. Wong <djwong(a)kernel.org> Signed-off-by: Wentao Liang <vulab(a)iscas.ac.cn> Signed-off-by: Carlos Maiolino <cem(a)kernel.org> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index c95fe1b1de4e..b1f9f156ec88 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -1404,8 +1404,11 @@ xfs_inactive( goto out; /* Try to clean out the cow blocks if there are any. */ - if (xfs_inode_has_cow_data(ip)) - xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, true); + if (xfs_inode_has_cow_data(ip)) { + error = xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, true); + if (error) + goto out; + } if (VFS_I(ip)->i_nlink != 0) { /*

9 months, 1 week

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FAILED: patch "[PATCH] hrtimers: Force migrate away hrtimers queued after" 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 53dac345395c0d2493cbc2f4c85fe38aef5b63f5 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025021056-sincere-reformist-1cc5@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 53dac345395c0d2493cbc2f4c85fe38aef5b63f5 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker <frederic(a)kernel.org> Date: Sat, 18 Jan 2025 00:24:33 +0100 Subject: [PATCH] hrtimers: Force migrate away hrtimers queued after CPUHP_AP_HRTIMERS_DYING hrtimers are migrated away from the dying CPU to any online target at the CPUHP_AP_HRTIMERS_DYING stage in order not to delay bandwidth timers handling tasks involved in the CPU hotplug forward progress. However wakeups can still be performed by the outgoing CPU after CPUHP_AP_HRTIMERS_DYING. Those can result again in bandwidth timers being armed. Depending on several considerations (crystal ball power management based election, earliest timer already enqueued, timer migration enabled or not), the target may eventually be the current CPU even if offline. If that happens, the timer is eventually ignored. The most notable example is RCU which had to deal with each and every of those wake-ups by deferring them to an online CPU, along with related workarounds: _ e787644caf76 (rcu: Defer RCU kthreads wakeup when CPU is dying) _ 9139f93209d1 (rcu/nocb: Fix RT throttling hrtimer armed from offline CPU) _ f7345ccc62a4 (rcu/nocb: Fix rcuog wake-up from offline softirq) The problem isn't confined to RCU though as the stop machine kthread (which runs CPUHP_AP_HRTIMERS_DYING) reports its completion at the end of its work through cpu_stop_signal_done() and performs a wake up that eventually arms the deadline server timer: WARNING: CPU: 94 PID: 588 at kernel/time/hrtimer.c:1086 hrtimer_start_range_ns+0x289/0x2d0 CPU: 94 UID: 0 PID: 588 Comm: migration/94 Not tainted Stopper: multi_cpu_stop+0x0/0x120 <- stop_machine_cpuslocked+0x66/0xc0 RIP: 0010:hrtimer_start_range_ns+0x289/0x2d0 Call Trace: <TASK> start_dl_timer enqueue_dl_entity dl_server_start enqueue_task_fair enqueue_task ttwu_do_activate try_to_wake_up complete cpu_stopper_thread Instead of providing yet another bandaid to work around the situation, fix it in the hrtimers infrastructure instead: always migrate away a timer to an online target whenever it is enqueued from an offline CPU. This will also allow to revert all the above RCU disgraceful hacks. Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier") Reported-by: Vlad Poenaru <vlad.wing(a)gmail.com> Reported-by: Usama Arif <usamaarif642(a)gmail.com> Signed-off-by: Frederic Weisbecker <frederic(a)kernel.org> Signed-off-by: Paul E. McKenney <paulmck(a)kernel.org> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Cc: stable(a)vger.kernel.org Tested-by: Paul E. McKenney <paulmck(a)kernel.org> Link: https://lore.kernel.org/all/20250117232433.24027-1-frederic@kernel.org Closes: 20241213203739.1519801-1-usamaarif642(a)gmail.com diff --git a/include/linux/hrtimer_defs.h b/include/linux/hrtimer_defs.h index c3b4b7ed7c16..84a5045f80f3 100644 --- a/include/linux/hrtimer_defs.h +++ b/include/linux/hrtimer_defs.h @@ -125,6 +125,7 @@ struct hrtimer_cpu_base { ktime_t softirq_expires_next; struct hrtimer *softirq_next_timer; struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES]; + call_single_data_t csd; } ____cacheline_aligned; diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 4fb81f8c6f1c..deb1aa32814e 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -58,6 +58,8 @@ #define HRTIMER_ACTIVE_SOFT (HRTIMER_ACTIVE_HARD << MASK_SHIFT) #define HRTIMER_ACTIVE_ALL (HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD) +static void retrigger_next_event(void *arg); + /* * The timer bases: * @@ -111,7 +113,8 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) = .clockid = CLOCK_TAI, .get_time = &ktime_get_clocktai, }, - } + }, + .csd = CSD_INIT(retrigger_next_event, NULL) }; static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = { @@ -124,6 +127,14 @@ static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = { [CLOCK_TAI] = HRTIMER_BASE_TAI, }; +static inline bool hrtimer_base_is_online(struct hrtimer_cpu_base *base) +{ + if (!IS_ENABLED(CONFIG_HOTPLUG_CPU)) + return true; + else + return likely(base->online); +} + /* * Functions and macros which are different for UP/SMP systems are kept in a * single place @@ -178,27 +189,54 @@ struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer, } /* - * We do not migrate the timer when it is expiring before the next - * event on the target cpu. When high resolution is enabled, we cannot - * reprogram the target cpu hardware and we would cause it to fire - * late. To keep it simple, we handle the high resolution enabled and - * disabled case similar. + * Check if the elected target is suitable considering its next + * event and the hotplug state of the current CPU. + * + * If the elected target is remote and its next event is after the timer + * to queue, then a remote reprogram is necessary. However there is no + * guarantee the IPI handling the operation would arrive in time to meet + * the high resolution deadline. In this case the local CPU becomes a + * preferred target, unless it is offline. + * + * High and low resolution modes are handled the same way for simplicity. * * Called with cpu_base->lock of target cpu held. */ -static int -hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base) +static bool hrtimer_suitable_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base, + struct hrtimer_cpu_base *new_cpu_base, + struct hrtimer_cpu_base *this_cpu_base) { ktime_t expires; + /* + * The local CPU clockevent can be reprogrammed. Also get_target_base() + * guarantees it is online. + */ + if (new_cpu_base == this_cpu_base) + return true; + + /* + * The offline local CPU can't be the default target if the + * next remote target event is after this timer. Keep the + * elected new base. An IPI will we issued to reprogram + * it as a last resort. + */ + if (!hrtimer_base_is_online(this_cpu_base)) + return true; + expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset); - return expires < new_base->cpu_base->expires_next; + + return expires >= new_base->cpu_base->expires_next; } -static inline -struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base, - int pinned) +static inline struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base, int pinned) { + if (!hrtimer_base_is_online(base)) { + int cpu = cpumask_any_and(cpu_online_mask, housekeeping_cpumask(HK_TYPE_TIMER)); + + return &per_cpu(hrtimer_bases, cpu); + } + #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON) if (static_branch_likely(&timers_migration_enabled) && !pinned) return &per_cpu(hrtimer_bases, get_nohz_timer_target()); @@ -249,8 +287,8 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base, raw_spin_unlock(&base->cpu_base->lock); raw_spin_lock(&new_base->cpu_base->lock); - if (new_cpu_base != this_cpu_base && - hrtimer_check_target(timer, new_base)) { + if (!hrtimer_suitable_target(timer, new_base, new_cpu_base, + this_cpu_base)) { raw_spin_unlock(&new_base->cpu_base->lock); raw_spin_lock(&base->cpu_base->lock); new_cpu_base = this_cpu_base; @@ -259,8 +297,7 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base, } WRITE_ONCE(timer->base, new_base); } else { - if (new_cpu_base != this_cpu_base && - hrtimer_check_target(timer, new_base)) { + if (!hrtimer_suitable_target(timer, new_base, new_cpu_base, this_cpu_base)) { new_cpu_base = this_cpu_base; goto again; } @@ -706,8 +743,6 @@ static inline int hrtimer_is_hres_enabled(void) return hrtimer_hres_enabled; } -static void retrigger_next_event(void *arg); - /* * Switch to high resolution mode */ @@ -1195,6 +1230,7 @@ static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, u64 delta_ns, const enum hrtimer_mode mode, struct hrtimer_clock_base *base) { + struct hrtimer_cpu_base *this_cpu_base = this_cpu_ptr(&hrtimer_bases); struct hrtimer_clock_base *new_base; bool force_local, first; @@ -1206,9 +1242,15 @@ static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, * and enforce reprogramming after it is queued no matter whether * it is the new first expiring timer again or not. */ - force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases); + force_local = base->cpu_base == this_cpu_base; force_local &= base->cpu_base->next_timer == timer; + /* + * Don't force local queuing if this enqueue happens on a unplugged + * CPU after hrtimer_cpu_dying() has been invoked. + */ + force_local &= this_cpu_base->online; + /* * Remove an active timer from the queue. In case it is not queued * on the current CPU, make sure that remove_hrtimer() updates the @@ -1238,8 +1280,27 @@ static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, } first = enqueue_hrtimer(timer, new_base, mode); - if (!force_local) - return first; + if (!force_local) { + /* + * If the current CPU base is online, then the timer is + * never queued on a remote CPU if it would be the first + * expiring timer there. + */ + if (hrtimer_base_is_online(this_cpu_base)) + return first; + + /* + * Timer was enqueued remote because the current base is + * already offline. If the timer is the first to expire, + * kick the remote CPU to reprogram the clock event. + */ + if (first) { + struct hrtimer_cpu_base *new_cpu_base = new_base->cpu_base; + + smp_call_function_single_async(new_cpu_base->cpu, &new_cpu_base->csd); + } + return 0; + } /* * Timer was forced to stay on the current CPU to avoid

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FAILED: patch "[PATCH] hrtimers: Force migrate away hrtimers queued after" 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 53dac345395c0d2493cbc2f4c85fe38aef5b63f5 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025021055-chimp-kinswoman-da90@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 53dac345395c0d2493cbc2f4c85fe38aef5b63f5 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker <frederic(a)kernel.org> Date: Sat, 18 Jan 2025 00:24:33 +0100 Subject: [PATCH] hrtimers: Force migrate away hrtimers queued after CPUHP_AP_HRTIMERS_DYING hrtimers are migrated away from the dying CPU to any online target at the CPUHP_AP_HRTIMERS_DYING stage in order not to delay bandwidth timers handling tasks involved in the CPU hotplug forward progress. However wakeups can still be performed by the outgoing CPU after CPUHP_AP_HRTIMERS_DYING. Those can result again in bandwidth timers being armed. Depending on several considerations (crystal ball power management based election, earliest timer already enqueued, timer migration enabled or not), the target may eventually be the current CPU even if offline. If that happens, the timer is eventually ignored. The most notable example is RCU which had to deal with each and every of those wake-ups by deferring them to an online CPU, along with related workarounds: _ e787644caf76 (rcu: Defer RCU kthreads wakeup when CPU is dying) _ 9139f93209d1 (rcu/nocb: Fix RT throttling hrtimer armed from offline CPU) _ f7345ccc62a4 (rcu/nocb: Fix rcuog wake-up from offline softirq) The problem isn't confined to RCU though as the stop machine kthread (which runs CPUHP_AP_HRTIMERS_DYING) reports its completion at the end of its work through cpu_stop_signal_done() and performs a wake up that eventually arms the deadline server timer: WARNING: CPU: 94 PID: 588 at kernel/time/hrtimer.c:1086 hrtimer_start_range_ns+0x289/0x2d0 CPU: 94 UID: 0 PID: 588 Comm: migration/94 Not tainted Stopper: multi_cpu_stop+0x0/0x120 <- stop_machine_cpuslocked+0x66/0xc0 RIP: 0010:hrtimer_start_range_ns+0x289/0x2d0 Call Trace: <TASK> start_dl_timer enqueue_dl_entity dl_server_start enqueue_task_fair enqueue_task ttwu_do_activate try_to_wake_up complete cpu_stopper_thread Instead of providing yet another bandaid to work around the situation, fix it in the hrtimers infrastructure instead: always migrate away a timer to an online target whenever it is enqueued from an offline CPU. This will also allow to revert all the above RCU disgraceful hacks. Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier") Reported-by: Vlad Poenaru <vlad.wing(a)gmail.com> Reported-by: Usama Arif <usamaarif642(a)gmail.com> Signed-off-by: Frederic Weisbecker <frederic(a)kernel.org> Signed-off-by: Paul E. McKenney <paulmck(a)kernel.org> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Cc: stable(a)vger.kernel.org Tested-by: Paul E. McKenney <paulmck(a)kernel.org> Link: https://lore.kernel.org/all/20250117232433.24027-1-frederic@kernel.org Closes: 20241213203739.1519801-1-usamaarif642(a)gmail.com diff --git a/include/linux/hrtimer_defs.h b/include/linux/hrtimer_defs.h index c3b4b7ed7c16..84a5045f80f3 100644 --- a/include/linux/hrtimer_defs.h +++ b/include/linux/hrtimer_defs.h @@ -125,6 +125,7 @@ struct hrtimer_cpu_base { ktime_t softirq_expires_next; struct hrtimer *softirq_next_timer; struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES]; + call_single_data_t csd; } ____cacheline_aligned; diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 4fb81f8c6f1c..deb1aa32814e 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -58,6 +58,8 @@ #define HRTIMER_ACTIVE_SOFT (HRTIMER_ACTIVE_HARD << MASK_SHIFT) #define HRTIMER_ACTIVE_ALL (HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD) +static void retrigger_next_event(void *arg); + /* * The timer bases: * @@ -111,7 +113,8 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) = .clockid = CLOCK_TAI, .get_time = &ktime_get_clocktai, }, - } + }, + .csd = CSD_INIT(retrigger_next_event, NULL) }; static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = { @@ -124,6 +127,14 @@ static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = { [CLOCK_TAI] = HRTIMER_BASE_TAI, }; +static inline bool hrtimer_base_is_online(struct hrtimer_cpu_base *base) +{ + if (!IS_ENABLED(CONFIG_HOTPLUG_CPU)) + return true; + else + return likely(base->online); +} + /* * Functions and macros which are different for UP/SMP systems are kept in a * single place @@ -178,27 +189,54 @@ struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer, } /* - * We do not migrate the timer when it is expiring before the next - * event on the target cpu. When high resolution is enabled, we cannot - * reprogram the target cpu hardware and we would cause it to fire - * late. To keep it simple, we handle the high resolution enabled and - * disabled case similar. + * Check if the elected target is suitable considering its next + * event and the hotplug state of the current CPU. + * + * If the elected target is remote and its next event is after the timer + * to queue, then a remote reprogram is necessary. However there is no + * guarantee the IPI handling the operation would arrive in time to meet + * the high resolution deadline. In this case the local CPU becomes a + * preferred target, unless it is offline. + * + * High and low resolution modes are handled the same way for simplicity. * * Called with cpu_base->lock of target cpu held. */ -static int -hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base) +static bool hrtimer_suitable_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base, + struct hrtimer_cpu_base *new_cpu_base, + struct hrtimer_cpu_base *this_cpu_base) { ktime_t expires; + /* + * The local CPU clockevent can be reprogrammed. Also get_target_base() + * guarantees it is online. + */ + if (new_cpu_base == this_cpu_base) + return true; + + /* + * The offline local CPU can't be the default target if the + * next remote target event is after this timer. Keep the + * elected new base. An IPI will we issued to reprogram + * it as a last resort. + */ + if (!hrtimer_base_is_online(this_cpu_base)) + return true; + expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset); - return expires < new_base->cpu_base->expires_next; + + return expires >= new_base->cpu_base->expires_next; } -static inline -struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base, - int pinned) +static inline struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base, int pinned) { + if (!hrtimer_base_is_online(base)) { + int cpu = cpumask_any_and(cpu_online_mask, housekeeping_cpumask(HK_TYPE_TIMER)); + + return &per_cpu(hrtimer_bases, cpu); + } + #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON) if (static_branch_likely(&timers_migration_enabled) && !pinned) return &per_cpu(hrtimer_bases, get_nohz_timer_target()); @@ -249,8 +287,8 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base, raw_spin_unlock(&base->cpu_base->lock); raw_spin_lock(&new_base->cpu_base->lock); - if (new_cpu_base != this_cpu_base && - hrtimer_check_target(timer, new_base)) { + if (!hrtimer_suitable_target(timer, new_base, new_cpu_base, + this_cpu_base)) { raw_spin_unlock(&new_base->cpu_base->lock); raw_spin_lock(&base->cpu_base->lock); new_cpu_base = this_cpu_base; @@ -259,8 +297,7 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base, } WRITE_ONCE(timer->base, new_base); } else { - if (new_cpu_base != this_cpu_base && - hrtimer_check_target(timer, new_base)) { + if (!hrtimer_suitable_target(timer, new_base, new_cpu_base, this_cpu_base)) { new_cpu_base = this_cpu_base; goto again; } @@ -706,8 +743,6 @@ static inline int hrtimer_is_hres_enabled(void) return hrtimer_hres_enabled; } -static void retrigger_next_event(void *arg); - /* * Switch to high resolution mode */ @@ -1195,6 +1230,7 @@ static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, u64 delta_ns, const enum hrtimer_mode mode, struct hrtimer_clock_base *base) { + struct hrtimer_cpu_base *this_cpu_base = this_cpu_ptr(&hrtimer_bases); struct hrtimer_clock_base *new_base; bool force_local, first; @@ -1206,9 +1242,15 @@ static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, * and enforce reprogramming after it is queued no matter whether * it is the new first expiring timer again or not. */ - force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases); + force_local = base->cpu_base == this_cpu_base; force_local &= base->cpu_base->next_timer == timer; + /* + * Don't force local queuing if this enqueue happens on a unplugged + * CPU after hrtimer_cpu_dying() has been invoked. + */ + force_local &= this_cpu_base->online; + /* * Remove an active timer from the queue. In case it is not queued * on the current CPU, make sure that remove_hrtimer() updates the @@ -1238,8 +1280,27 @@ static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, } first = enqueue_hrtimer(timer, new_base, mode); - if (!force_local) - return first; + if (!force_local) { + /* + * If the current CPU base is online, then the timer is + * never queued on a remote CPU if it would be the first + * expiring timer there. + */ + if (hrtimer_base_is_online(this_cpu_base)) + return first; + + /* + * Timer was enqueued remote because the current base is + * already offline. If the timer is the first to expire, + * kick the remote CPU to reprogram the clock event. + */ + if (first) { + struct hrtimer_cpu_base *new_cpu_base = new_base->cpu_base; + + smp_call_function_single_async(new_cpu_base->cpu, &new_cpu_base->csd); + } + return 0; + } /* * Timer was forced to stay on the current CPU to avoid

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